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1
1090-1093
28) The situation has obvious spherical symmetry The field at any point P, outside or inside, can depend only on r (the radial distance from the centre of the shell to the point) and must be radial (i e
1
1091-1094
The situation has obvious spherical symmetry The field at any point P, outside or inside, can depend only on r (the radial distance from the centre of the shell to the point) and must be radial (i e , along the radius vector)
1
1092-1095
The field at any point P, outside or inside, can depend only on r (the radial distance from the centre of the shell to the point) and must be radial (i e , along the radius vector) (i) Field outside the shell: Consider a point P outside the shell with radius vector r
1
1093-1096
e , along the radius vector) (i) Field outside the shell: Consider a point P outside the shell with radius vector r To calculate E at P, we take the Gaussian surface to be a sphere of radius r and with centre O, passing through P
1
1094-1097
, along the radius vector) (i) Field outside the shell: Consider a point P outside the shell with radius vector r To calculate E at P, we take the Gaussian surface to be a sphere of radius r and with centre O, passing through P All points on this sphere are equivalent relative to the given charged configuration
1
1095-1098
(i) Field outside the shell: Consider a point P outside the shell with radius vector r To calculate E at P, we take the Gaussian surface to be a sphere of radius r and with centre O, passing through P All points on this sphere are equivalent relative to the given charged configuration (That is what we mean by spherical symmetry
1
1096-1099
To calculate E at P, we take the Gaussian surface to be a sphere of radius r and with centre O, passing through P All points on this sphere are equivalent relative to the given charged configuration (That is what we mean by spherical symmetry ) The electric field at each point of the Gaussian surface, therefore, has the same magnitude E and is along the radius vector at each point
1
1097-1100
All points on this sphere are equivalent relative to the given charged configuration (That is what we mean by spherical symmetry ) The electric field at each point of the Gaussian surface, therefore, has the same magnitude E and is along the radius vector at each point Thus, E and DS at every point are parallel and the flux through each element is E DS
1
1098-1101
(That is what we mean by spherical symmetry ) The electric field at each point of the Gaussian surface, therefore, has the same magnitude E and is along the radius vector at each point Thus, E and DS at every point are parallel and the flux through each element is E DS Summing over all DS, the flux through the Gaussian surface is E × 4 p r 2
1
1099-1102
) The electric field at each point of the Gaussian surface, therefore, has the same magnitude E and is along the radius vector at each point Thus, E and DS at every point are parallel and the flux through each element is E DS Summing over all DS, the flux through the Gaussian surface is E × 4 p r 2 The charge enclosed is s × 4 p R 2
1
1100-1103
Thus, E and DS at every point are parallel and the flux through each element is E DS Summing over all DS, the flux through the Gaussian surface is E × 4 p r 2 The charge enclosed is s × 4 p R 2 By Gauss’s law E × 4 p r 2 = 2 0 4 R εσ π Or, 2 2 2 0 0 4 R q E r r εσ ε = = π where q = 4 p R2 s is the total charge on the spherical shell
1
1101-1104
Summing over all DS, the flux through the Gaussian surface is E × 4 p r 2 The charge enclosed is s × 4 p R 2 By Gauss’s law E × 4 p r 2 = 2 0 4 R εσ π Or, 2 2 2 0 0 4 R q E r r εσ ε = = π where q = 4 p R2 s is the total charge on the spherical shell Vectorially, 2 0 ˆ 4 q εr = π E r (1
1
1102-1105
The charge enclosed is s × 4 p R 2 By Gauss’s law E × 4 p r 2 = 2 0 4 R εσ π Or, 2 2 2 0 0 4 R q E r r εσ ε = = π where q = 4 p R2 s is the total charge on the spherical shell Vectorially, 2 0 ˆ 4 q εr = π E r (1 34) The electric field is directed outward if q > 0 and inward if q < 0
1
1103-1106
By Gauss’s law E × 4 p r 2 = 2 0 4 R εσ π Or, 2 2 2 0 0 4 R q E r r εσ ε = = π where q = 4 p R2 s is the total charge on the spherical shell Vectorially, 2 0 ˆ 4 q εr = π E r (1 34) The electric field is directed outward if q > 0 and inward if q < 0 This, however, is exactly the field produced by a charge q placed at the centre O
1
1104-1107
Vectorially, 2 0 ˆ 4 q εr = π E r (1 34) The electric field is directed outward if q > 0 and inward if q < 0 This, however, is exactly the field produced by a charge q placed at the centre O Thus for points outside the shell, the field due to a uniformly charged shell is as if the entire charge of the shell is concentrated at its centre
1
1105-1108
34) The electric field is directed outward if q > 0 and inward if q < 0 This, however, is exactly the field produced by a charge q placed at the centre O Thus for points outside the shell, the field due to a uniformly charged shell is as if the entire charge of the shell is concentrated at its centre (ii) Field inside the shell: In Fig
1
1106-1109
This, however, is exactly the field produced by a charge q placed at the centre O Thus for points outside the shell, the field due to a uniformly charged shell is as if the entire charge of the shell is concentrated at its centre (ii) Field inside the shell: In Fig 1
1
1107-1110
Thus for points outside the shell, the field due to a uniformly charged shell is as if the entire charge of the shell is concentrated at its centre (ii) Field inside the shell: In Fig 1 28(b), the point P is inside the shell
1
1108-1111
(ii) Field inside the shell: In Fig 1 28(b), the point P is inside the shell The Gaussian surface is again a sphere through P centred at O
1
1109-1112
1 28(b), the point P is inside the shell The Gaussian surface is again a sphere through P centred at O FIGURE 1
1
1110-1113
28(b), the point P is inside the shell The Gaussian surface is again a sphere through P centred at O FIGURE 1 28 Gaussian surfaces for a point with (a) r > R, (b) r < R
1
1111-1114
The Gaussian surface is again a sphere through P centred at O FIGURE 1 28 Gaussian surfaces for a point with (a) r > R, (b) r < R Rationalised 2023-24 36 Physics EXAMPLE 1
1
1112-1115
FIGURE 1 28 Gaussian surfaces for a point with (a) r > R, (b) r < R Rationalised 2023-24 36 Physics EXAMPLE 1 12 The flux through the Gaussian surface, calculated as before, is E × 4 p r2
1
1113-1116
28 Gaussian surfaces for a point with (a) r > R, (b) r < R Rationalised 2023-24 36 Physics EXAMPLE 1 12 The flux through the Gaussian surface, calculated as before, is E × 4 p r2 However, in this case, the Gaussian surface encloses no charge
1
1114-1117
Rationalised 2023-24 36 Physics EXAMPLE 1 12 The flux through the Gaussian surface, calculated as before, is E × 4 p r2 However, in this case, the Gaussian surface encloses no charge Gauss’s law then gives E × 4 p r2 = 0 i
1
1115-1118
12 The flux through the Gaussian surface, calculated as before, is E × 4 p r2 However, in this case, the Gaussian surface encloses no charge Gauss’s law then gives E × 4 p r2 = 0 i e
1
1116-1119
However, in this case, the Gaussian surface encloses no charge Gauss’s law then gives E × 4 p r2 = 0 i e , E = 0 (r < R ) (1
1
1117-1120
Gauss’s law then gives E × 4 p r2 = 0 i e , E = 0 (r < R ) (1 35) that is, the field due to a uniformly charged thin shell is zero at all points inside the shell*
1
1118-1121
e , E = 0 (r < R ) (1 35) that is, the field due to a uniformly charged thin shell is zero at all points inside the shell* This important result is a direct consequence of Gauss’s law which follows from Coulomb’s law
1
1119-1122
, E = 0 (r < R ) (1 35) that is, the field due to a uniformly charged thin shell is zero at all points inside the shell* This important result is a direct consequence of Gauss’s law which follows from Coulomb’s law The experimental verification of this result confirms the 1/r2 dependence in Coulomb’s law
1
1120-1123
35) that is, the field due to a uniformly charged thin shell is zero at all points inside the shell* This important result is a direct consequence of Gauss’s law which follows from Coulomb’s law The experimental verification of this result confirms the 1/r2 dependence in Coulomb’s law Example 1
1
1121-1124
This important result is a direct consequence of Gauss’s law which follows from Coulomb’s law The experimental verification of this result confirms the 1/r2 dependence in Coulomb’s law Example 1 12 An early model for an atom considered it to have a positively charged point nucleus of charge Ze, surrounded by a uniform density of negative charge up to a radius R
1
1122-1125
The experimental verification of this result confirms the 1/r2 dependence in Coulomb’s law Example 1 12 An early model for an atom considered it to have a positively charged point nucleus of charge Ze, surrounded by a uniform density of negative charge up to a radius R The atom as a whole is neutral
1
1123-1126
Example 1 12 An early model for an atom considered it to have a positively charged point nucleus of charge Ze, surrounded by a uniform density of negative charge up to a radius R The atom as a whole is neutral For this model, what is the electric field at a distance r from the nucleus
1
1124-1127
12 An early model for an atom considered it to have a positively charged point nucleus of charge Ze, surrounded by a uniform density of negative charge up to a radius R The atom as a whole is neutral For this model, what is the electric field at a distance r from the nucleus FIGURE 1
1
1125-1128
The atom as a whole is neutral For this model, what is the electric field at a distance r from the nucleus FIGURE 1 29 Solution The charge distribution for this model of the atom is as shown in Fig
1
1126-1129
For this model, what is the electric field at a distance r from the nucleus FIGURE 1 29 Solution The charge distribution for this model of the atom is as shown in Fig 1
1
1127-1130
FIGURE 1 29 Solution The charge distribution for this model of the atom is as shown in Fig 1 29
1
1128-1131
29 Solution The charge distribution for this model of the atom is as shown in Fig 1 29 The total negative charge in the uniform spherical charge distribution of radius R must be –Z e, since the atom (nucleus of charge Z e + negative charge) is neutral
1
1129-1132
1 29 The total negative charge in the uniform spherical charge distribution of radius R must be –Z e, since the atom (nucleus of charge Z e + negative charge) is neutral This immediately gives us the negative charge density r, since we must have 3 4 0– 3 R Ze ρ π = or 3 3 4 Ze R ρ = − π To find the electric field E(r) at a point P which is a distance r away from the nucleus, we use Gauss’s law
1
1130-1133
29 The total negative charge in the uniform spherical charge distribution of radius R must be –Z e, since the atom (nucleus of charge Z e + negative charge) is neutral This immediately gives us the negative charge density r, since we must have 3 4 0– 3 R Ze ρ π = or 3 3 4 Ze R ρ = − π To find the electric field E(r) at a point P which is a distance r away from the nucleus, we use Gauss’s law Because of the spherical symmetry of the charge distribution, the magnitude of the electric field E(r) depends only on the radial distance, no matter what the direction of r
1
1131-1134
The total negative charge in the uniform spherical charge distribution of radius R must be –Z e, since the atom (nucleus of charge Z e + negative charge) is neutral This immediately gives us the negative charge density r, since we must have 3 4 0– 3 R Ze ρ π = or 3 3 4 Ze R ρ = − π To find the electric field E(r) at a point P which is a distance r away from the nucleus, we use Gauss’s law Because of the spherical symmetry of the charge distribution, the magnitude of the electric field E(r) depends only on the radial distance, no matter what the direction of r Its direction is along (or opposite to) the radius vector r from the origin to the point P
1
1132-1135
This immediately gives us the negative charge density r, since we must have 3 4 0– 3 R Ze ρ π = or 3 3 4 Ze R ρ = − π To find the electric field E(r) at a point P which is a distance r away from the nucleus, we use Gauss’s law Because of the spherical symmetry of the charge distribution, the magnitude of the electric field E(r) depends only on the radial distance, no matter what the direction of r Its direction is along (or opposite to) the radius vector r from the origin to the point P The obvious Gaussian surface is a spherical surface centred at the nucleus
1
1133-1136
Because of the spherical symmetry of the charge distribution, the magnitude of the electric field E(r) depends only on the radial distance, no matter what the direction of r Its direction is along (or opposite to) the radius vector r from the origin to the point P The obvious Gaussian surface is a spherical surface centred at the nucleus We consider two situations, namely, r < R and r > R
1
1134-1137
Its direction is along (or opposite to) the radius vector r from the origin to the point P The obvious Gaussian surface is a spherical surface centred at the nucleus We consider two situations, namely, r < R and r > R (i) r < R : The electric flux f enclosed by the spherical surface is f = E (r) × 4 p r 2 * Compare this with a uniform mass shell discussed in Section 7
1
1135-1138
The obvious Gaussian surface is a spherical surface centred at the nucleus We consider two situations, namely, r < R and r > R (i) r < R : The electric flux f enclosed by the spherical surface is f = E (r) × 4 p r 2 * Compare this with a uniform mass shell discussed in Section 7 5 of Class XI Textbook of Physics
1
1136-1139
We consider two situations, namely, r < R and r > R (i) r < R : The electric flux f enclosed by the spherical surface is f = E (r) × 4 p r 2 * Compare this with a uniform mass shell discussed in Section 7 5 of Class XI Textbook of Physics Rationalised 2023-24 Electric Charges and Fields 37 EXAMPLE 1
1
1137-1140
(i) r < R : The electric flux f enclosed by the spherical surface is f = E (r) × 4 p r 2 * Compare this with a uniform mass shell discussed in Section 7 5 of Class XI Textbook of Physics Rationalised 2023-24 Electric Charges and Fields 37 EXAMPLE 1 12 where E (r) is the magnitude of the electric field at r
1
1138-1141
5 of Class XI Textbook of Physics Rationalised 2023-24 Electric Charges and Fields 37 EXAMPLE 1 12 where E (r) is the magnitude of the electric field at r This is because the field at any point on the spherical Gaussian surface has the same direction as the normal to the surface there, and has the same magnitude at all points on the surface
1
1139-1142
Rationalised 2023-24 Electric Charges and Fields 37 EXAMPLE 1 12 where E (r) is the magnitude of the electric field at r This is because the field at any point on the spherical Gaussian surface has the same direction as the normal to the surface there, and has the same magnitude at all points on the surface The charge q enclosed by the Gaussian surface is the positive nuclear charge and the negative charge within the sphere of radius r, i
1
1140-1143
12 where E (r) is the magnitude of the electric field at r This is because the field at any point on the spherical Gaussian surface has the same direction as the normal to the surface there, and has the same magnitude at all points on the surface The charge q enclosed by the Gaussian surface is the positive nuclear charge and the negative charge within the sphere of radius r, i e
1
1141-1144
This is because the field at any point on the spherical Gaussian surface has the same direction as the normal to the surface there, and has the same magnitude at all points on the surface The charge q enclosed by the Gaussian surface is the positive nuclear charge and the negative charge within the sphere of radius r, i e , 3 4 3 r q Z e ρ π = + Substituting for the charge density r obtained earlier, we have 3 3 r q Z e Z e R = − Gauss’s law then gives, 2 3 0 1 ( ) ; 4 Z e r E r r R r R ε = − < π The electric field is directed radially outward
1
1142-1145
The charge q enclosed by the Gaussian surface is the positive nuclear charge and the negative charge within the sphere of radius r, i e , 3 4 3 r q Z e ρ π = + Substituting for the charge density r obtained earlier, we have 3 3 r q Z e Z e R = − Gauss’s law then gives, 2 3 0 1 ( ) ; 4 Z e r E r r R r R ε = − < π The electric field is directed radially outward (ii) r > R: In this case, the total charge enclosed by the Gaussian spherical surface is zero since the atom is neutral
1
1143-1146
e , 3 4 3 r q Z e ρ π = + Substituting for the charge density r obtained earlier, we have 3 3 r q Z e Z e R = − Gauss’s law then gives, 2 3 0 1 ( ) ; 4 Z e r E r r R r R ε = − < π The electric field is directed radially outward (ii) r > R: In this case, the total charge enclosed by the Gaussian spherical surface is zero since the atom is neutral Thus, from Gauss’s law, E (r) × 4 p r 2 = 0 or E (r) = 0; r > R At r = R, both cases give the same result: E = 0
1
1144-1147
, 3 4 3 r q Z e ρ π = + Substituting for the charge density r obtained earlier, we have 3 3 r q Z e Z e R = − Gauss’s law then gives, 2 3 0 1 ( ) ; 4 Z e r E r r R r R ε = − < π The electric field is directed radially outward (ii) r > R: In this case, the total charge enclosed by the Gaussian spherical surface is zero since the atom is neutral Thus, from Gauss’s law, E (r) × 4 p r 2 = 0 or E (r) = 0; r > R At r = R, both cases give the same result: E = 0 SUMMARY 1
1
1145-1148
(ii) r > R: In this case, the total charge enclosed by the Gaussian spherical surface is zero since the atom is neutral Thus, from Gauss’s law, E (r) × 4 p r 2 = 0 or E (r) = 0; r > R At r = R, both cases give the same result: E = 0 SUMMARY 1 Electric and magnetic forces determine the properties of atoms, molecules and bulk matter
1
1146-1149
Thus, from Gauss’s law, E (r) × 4 p r 2 = 0 or E (r) = 0; r > R At r = R, both cases give the same result: E = 0 SUMMARY 1 Electric and magnetic forces determine the properties of atoms, molecules and bulk matter 2
1
1147-1150
SUMMARY 1 Electric and magnetic forces determine the properties of atoms, molecules and bulk matter 2 From simple experiments on frictional electricity, one can infer that there are two types of charges in nature; and that like charges repel and unlike charges attract
1
1148-1151
Electric and magnetic forces determine the properties of atoms, molecules and bulk matter 2 From simple experiments on frictional electricity, one can infer that there are two types of charges in nature; and that like charges repel and unlike charges attract By convention, the charge on a glass rod rubbed with silk is positive; that on a plastic rod rubbed with fur is then negative
1
1149-1152
2 From simple experiments on frictional electricity, one can infer that there are two types of charges in nature; and that like charges repel and unlike charges attract By convention, the charge on a glass rod rubbed with silk is positive; that on a plastic rod rubbed with fur is then negative 3
1
1150-1153
From simple experiments on frictional electricity, one can infer that there are two types of charges in nature; and that like charges repel and unlike charges attract By convention, the charge on a glass rod rubbed with silk is positive; that on a plastic rod rubbed with fur is then negative 3 Conductors allow movement of electric charge through them, insulators do not
1
1151-1154
By convention, the charge on a glass rod rubbed with silk is positive; that on a plastic rod rubbed with fur is then negative 3 Conductors allow movement of electric charge through them, insulators do not In metals, the mobile charges are electrons; in electrolytes both positive and negative ions are mobile
1
1152-1155
3 Conductors allow movement of electric charge through them, insulators do not In metals, the mobile charges are electrons; in electrolytes both positive and negative ions are mobile 4
1
1153-1156
Conductors allow movement of electric charge through them, insulators do not In metals, the mobile charges are electrons; in electrolytes both positive and negative ions are mobile 4 Electric charge has three basic properties: quantisation, additivity and conservation
1
1154-1157
In metals, the mobile charges are electrons; in electrolytes both positive and negative ions are mobile 4 Electric charge has three basic properties: quantisation, additivity and conservation Quantisation of electric charge means that total charge (q) of a body is always an integral multiple of a basic quantum of charge (e) i
1
1155-1158
4 Electric charge has three basic properties: quantisation, additivity and conservation Quantisation of electric charge means that total charge (q) of a body is always an integral multiple of a basic quantum of charge (e) i e
1
1156-1159
Electric charge has three basic properties: quantisation, additivity and conservation Quantisation of electric charge means that total charge (q) of a body is always an integral multiple of a basic quantum of charge (e) i e , q = n e, where n = 0, ±1, ±2, ±3,
1
1157-1160
Quantisation of electric charge means that total charge (q) of a body is always an integral multiple of a basic quantum of charge (e) i e , q = n e, where n = 0, ±1, ±2, ±3, Proton and electron have charges +e, –e, respectively
1
1158-1161
e , q = n e, where n = 0, ±1, ±2, ±3, Proton and electron have charges +e, –e, respectively For macroscopic charges for which n is a very large number, quantisation of charge can be ignored
1
1159-1162
, q = n e, where n = 0, ±1, ±2, ±3, Proton and electron have charges +e, –e, respectively For macroscopic charges for which n is a very large number, quantisation of charge can be ignored Additivity of electric charges means that the total charge of a system is the algebraic sum (i
1
1160-1163
Proton and electron have charges +e, –e, respectively For macroscopic charges for which n is a very large number, quantisation of charge can be ignored Additivity of electric charges means that the total charge of a system is the algebraic sum (i e
1
1161-1164
For macroscopic charges for which n is a very large number, quantisation of charge can be ignored Additivity of electric charges means that the total charge of a system is the algebraic sum (i e , the sum taking into account proper signs) of all individual charges in the system
1
1162-1165
Additivity of electric charges means that the total charge of a system is the algebraic sum (i e , the sum taking into account proper signs) of all individual charges in the system Conservation of electric charges means that the total charge of an isolated system remains unchanged with time
1
1163-1166
e , the sum taking into account proper signs) of all individual charges in the system Conservation of electric charges means that the total charge of an isolated system remains unchanged with time This means that when Rationalised 2023-24 38 Physics bodies are charged through friction, there is a transfer of electric charge from one body to another, but no creation or destruction of charge
1
1164-1167
, the sum taking into account proper signs) of all individual charges in the system Conservation of electric charges means that the total charge of an isolated system remains unchanged with time This means that when Rationalised 2023-24 38 Physics bodies are charged through friction, there is a transfer of electric charge from one body to another, but no creation or destruction of charge 5
1
1165-1168
Conservation of electric charges means that the total charge of an isolated system remains unchanged with time This means that when Rationalised 2023-24 38 Physics bodies are charged through friction, there is a transfer of electric charge from one body to another, but no creation or destruction of charge 5 Coulomb’s Law: The mutual electrostatic force between two point charges q1 and q2 is proportional to the product q1q2 and inversely proportional to the square of the distance r21 separating them
1
1166-1169
This means that when Rationalised 2023-24 38 Physics bodies are charged through friction, there is a transfer of electric charge from one body to another, but no creation or destruction of charge 5 Coulomb’s Law: The mutual electrostatic force between two point charges q1 and q2 is proportional to the product q1q2 and inversely proportional to the square of the distance r21 separating them Mathematically, F21 = force on q2 due to 1 2 1 21 2 21 ˆ k (q q ) q r = r where ˆr21 is a unit vector in the direction from q1 to q2 and k = 0 1 4 ε π is the constant of proportionality
1
1167-1170
5 Coulomb’s Law: The mutual electrostatic force between two point charges q1 and q2 is proportional to the product q1q2 and inversely proportional to the square of the distance r21 separating them Mathematically, F21 = force on q2 due to 1 2 1 21 2 21 ˆ k (q q ) q r = r where ˆr21 is a unit vector in the direction from q1 to q2 and k = 0 1 4 ε π is the constant of proportionality In SI units, the unit of charge is coulomb
1
1168-1171
Coulomb’s Law: The mutual electrostatic force between two point charges q1 and q2 is proportional to the product q1q2 and inversely proportional to the square of the distance r21 separating them Mathematically, F21 = force on q2 due to 1 2 1 21 2 21 ˆ k (q q ) q r = r where ˆr21 is a unit vector in the direction from q1 to q2 and k = 0 1 4 ε π is the constant of proportionality In SI units, the unit of charge is coulomb The experimental value of the constant e0 is e0 = 8
1
1169-1172
Mathematically, F21 = force on q2 due to 1 2 1 21 2 21 ˆ k (q q ) q r = r where ˆr21 is a unit vector in the direction from q1 to q2 and k = 0 1 4 ε π is the constant of proportionality In SI units, the unit of charge is coulomb The experimental value of the constant e0 is e0 = 8 854 × 10–12 C2 N–1 m–2 The approximate value of k is k = 9 × 109 N m2 C–2 6
1
1170-1173
In SI units, the unit of charge is coulomb The experimental value of the constant e0 is e0 = 8 854 × 10–12 C2 N–1 m–2 The approximate value of k is k = 9 × 109 N m2 C–2 6 The ratio of electric force and gravitational force between a proton and an electron is 2 39 2 4 10 e p k e
1
1171-1174
The experimental value of the constant e0 is e0 = 8 854 × 10–12 C2 N–1 m–2 The approximate value of k is k = 9 × 109 N m2 C–2 6 The ratio of electric force and gravitational force between a proton and an electron is 2 39 2 4 10 e p k e G m m ≅ × 7
1
1172-1175
854 × 10–12 C2 N–1 m–2 The approximate value of k is k = 9 × 109 N m2 C–2 6 The ratio of electric force and gravitational force between a proton and an electron is 2 39 2 4 10 e p k e G m m ≅ × 7 Superposition Principle: The principle is based on the property that the forces with which two charges attract or repel each other are not affected by the presence of a third (or more) additional charge(s)
1
1173-1176
The ratio of electric force and gravitational force between a proton and an electron is 2 39 2 4 10 e p k e G m m ≅ × 7 Superposition Principle: The principle is based on the property that the forces with which two charges attract or repel each other are not affected by the presence of a third (or more) additional charge(s) For an assembly of charges q1, q2, q3,
1
1174-1177
G m m ≅ × 7 Superposition Principle: The principle is based on the property that the forces with which two charges attract or repel each other are not affected by the presence of a third (or more) additional charge(s) For an assembly of charges q1, q2, q3, , the force on any charge, say q1, is the vector sum of the force on q1 due to q2, the force on q1 due to q3, and so on
1
1175-1178
Superposition Principle: The principle is based on the property that the forces with which two charges attract or repel each other are not affected by the presence of a third (or more) additional charge(s) For an assembly of charges q1, q2, q3, , the force on any charge, say q1, is the vector sum of the force on q1 due to q2, the force on q1 due to q3, and so on For each pair, the force is given by the Coulomb’s law for two charges stated earlier
1
1176-1179
For an assembly of charges q1, q2, q3, , the force on any charge, say q1, is the vector sum of the force on q1 due to q2, the force on q1 due to q3, and so on For each pair, the force is given by the Coulomb’s law for two charges stated earlier 8
1
1177-1180
, the force on any charge, say q1, is the vector sum of the force on q1 due to q2, the force on q1 due to q3, and so on For each pair, the force is given by the Coulomb’s law for two charges stated earlier 8 The electric field E at a point due to a charge configuration is the force on a small positive test charge q placed at the point divided by the magnitude of the charge
1
1178-1181
For each pair, the force is given by the Coulomb’s law for two charges stated earlier 8 The electric field E at a point due to a charge configuration is the force on a small positive test charge q placed at the point divided by the magnitude of the charge Electric field due to a point charge q has a magnitude |q|/4pe0r2; it is radially outwards from q, if q is positive, and radially inwards if q is negative
1
1179-1182
8 The electric field E at a point due to a charge configuration is the force on a small positive test charge q placed at the point divided by the magnitude of the charge Electric field due to a point charge q has a magnitude |q|/4pe0r2; it is radially outwards from q, if q is positive, and radially inwards if q is negative Like Coulomb force, electric field also satisfies superposition principle
1
1180-1183
The electric field E at a point due to a charge configuration is the force on a small positive test charge q placed at the point divided by the magnitude of the charge Electric field due to a point charge q has a magnitude |q|/4pe0r2; it is radially outwards from q, if q is positive, and radially inwards if q is negative Like Coulomb force, electric field also satisfies superposition principle 9
1
1181-1184
Electric field due to a point charge q has a magnitude |q|/4pe0r2; it is radially outwards from q, if q is positive, and radially inwards if q is negative Like Coulomb force, electric field also satisfies superposition principle 9 An electric field line is a curve drawn in such a way that the tangent at each point on the curve gives the direction of electric field at that point
1
1182-1185
Like Coulomb force, electric field also satisfies superposition principle 9 An electric field line is a curve drawn in such a way that the tangent at each point on the curve gives the direction of electric field at that point The relative closeness of field lines indicates the relative strength of electric field at different points; they crowd near each other in regions of strong electric field and are far apart where the electric field is weak
1
1183-1186
9 An electric field line is a curve drawn in such a way that the tangent at each point on the curve gives the direction of electric field at that point The relative closeness of field lines indicates the relative strength of electric field at different points; they crowd near each other in regions of strong electric field and are far apart where the electric field is weak In regions of constant electric field, the field lines are uniformly spaced parallel straight lines
1
1184-1187
An electric field line is a curve drawn in such a way that the tangent at each point on the curve gives the direction of electric field at that point The relative closeness of field lines indicates the relative strength of electric field at different points; they crowd near each other in regions of strong electric field and are far apart where the electric field is weak In regions of constant electric field, the field lines are uniformly spaced parallel straight lines 10
1
1185-1188
The relative closeness of field lines indicates the relative strength of electric field at different points; they crowd near each other in regions of strong electric field and are far apart where the electric field is weak In regions of constant electric field, the field lines are uniformly spaced parallel straight lines 10 Some of the important properties of field lines are: (i) Field lines are continuous curves without any breaks
1
1186-1189
In regions of constant electric field, the field lines are uniformly spaced parallel straight lines 10 Some of the important properties of field lines are: (i) Field lines are continuous curves without any breaks (ii) Two field lines cannot cross each other
1
1187-1190
10 Some of the important properties of field lines are: (i) Field lines are continuous curves without any breaks (ii) Two field lines cannot cross each other (iii) Electrostatic field lines start at positive charges and end at negative charges —they cannot form closed loops
1
1188-1191
Some of the important properties of field lines are: (i) Field lines are continuous curves without any breaks (ii) Two field lines cannot cross each other (iii) Electrostatic field lines start at positive charges and end at negative charges —they cannot form closed loops 11
1
1189-1192
(ii) Two field lines cannot cross each other (iii) Electrostatic field lines start at positive charges and end at negative charges —they cannot form closed loops 11 An electric dipole is a pair of equal and opposite charges q and –q separated by some distance 2a