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139-142
8) h and hΒ’ will be taken positive or negative in accordance with the accepted sign convention In triangles AΒ’BΒ’P and ABP, we have, B A B P BA BP β€² β€² β€² = With the sign convention, this becomes Rationalised 2023-24 Physics 226 – – h v h u β€² = – so that m = – h v h u β€² = (9 9) We have derived here the mirror equation, Eq (9
9
140-143
In triangles AΒ’BΒ’P and ABP, we have, B A B P BA BP β€² β€² β€² = With the sign convention, this becomes Rationalised 2023-24 Physics 226 – – h v h u β€² = – so that m = – h v h u β€² = (9 9) We have derived here the mirror equation, Eq (9 7), and the magnification formula, Eq
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141-144
9) We have derived here the mirror equation, Eq (9 7), and the magnification formula, Eq (9
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142-145
(9 7), and the magnification formula, Eq (9 9), for the case of real, inverted image formed by a concave mirror
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143-146
7), and the magnification formula, Eq (9 9), for the case of real, inverted image formed by a concave mirror With the proper use of sign convention, these are, in fact, valid for all the cases of reflection by a spherical mirror (concave or convex) whether the image formed is real or virtual
9
144-147
(9 9), for the case of real, inverted image formed by a concave mirror With the proper use of sign convention, these are, in fact, valid for all the cases of reflection by a spherical mirror (concave or convex) whether the image formed is real or virtual Figure 9
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145-148
9), for the case of real, inverted image formed by a concave mirror With the proper use of sign convention, these are, in fact, valid for all the cases of reflection by a spherical mirror (concave or convex) whether the image formed is real or virtual Figure 9 6 shows the ray diagrams for virtual image formed by a concave and convex mirror
9
146-149
With the proper use of sign convention, these are, in fact, valid for all the cases of reflection by a spherical mirror (concave or convex) whether the image formed is real or virtual Figure 9 6 shows the ray diagrams for virtual image formed by a concave and convex mirror You should verify that Eqs
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147-150
Figure 9 6 shows the ray diagrams for virtual image formed by a concave and convex mirror You should verify that Eqs (9
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148-151
6 shows the ray diagrams for virtual image formed by a concave and convex mirror You should verify that Eqs (9 7) and (9
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149-152
You should verify that Eqs (9 7) and (9 9) are valid for these cases as well
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150-153
(9 7) and (9 9) are valid for these cases as well FIGURE 9
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151-154
7) and (9 9) are valid for these cases as well FIGURE 9 6 Image formation by (a) a concave mirror with object between P and F, and (b) a convex mirror
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152-155
9) are valid for these cases as well FIGURE 9 6 Image formation by (a) a concave mirror with object between P and F, and (b) a convex mirror EXAMPLE 9
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153-156
FIGURE 9 6 Image formation by (a) a concave mirror with object between P and F, and (b) a convex mirror EXAMPLE 9 1 Example 9
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154-157
6 Image formation by (a) a concave mirror with object between P and F, and (b) a convex mirror EXAMPLE 9 1 Example 9 1 Suppose that the lower half of the concave mirror’s reflecting surface in Fig
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155-158
EXAMPLE 9 1 Example 9 1 Suppose that the lower half of the concave mirror’s reflecting surface in Fig 9
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156-159
1 Example 9 1 Suppose that the lower half of the concave mirror’s reflecting surface in Fig 9 6 is covered with an opaque (non-reflective) material
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157-160
1 Suppose that the lower half of the concave mirror’s reflecting surface in Fig 9 6 is covered with an opaque (non-reflective) material What effect will this have on the image of an object placed in front of the mirror
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158-161
9 6 is covered with an opaque (non-reflective) material What effect will this have on the image of an object placed in front of the mirror Solution You may think that the image will now show only half of the object, but taking the laws of reflection to be true for all points of the remaining part of the mirror, the image will be that of the whole object
9
159-162
6 is covered with an opaque (non-reflective) material What effect will this have on the image of an object placed in front of the mirror Solution You may think that the image will now show only half of the object, but taking the laws of reflection to be true for all points of the remaining part of the mirror, the image will be that of the whole object However, as the area of the reflecting surface has been reduced, the intensity of the image will be low (in this case, half)
9
160-163
What effect will this have on the image of an object placed in front of the mirror Solution You may think that the image will now show only half of the object, but taking the laws of reflection to be true for all points of the remaining part of the mirror, the image will be that of the whole object However, as the area of the reflecting surface has been reduced, the intensity of the image will be low (in this case, half) Example 9
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161-164
Solution You may think that the image will now show only half of the object, but taking the laws of reflection to be true for all points of the remaining part of the mirror, the image will be that of the whole object However, as the area of the reflecting surface has been reduced, the intensity of the image will be low (in this case, half) Example 9 2 A mobile phone lies along the principal axis of a concave mirror, as shown in Fig
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162-165
However, as the area of the reflecting surface has been reduced, the intensity of the image will be low (in this case, half) Example 9 2 A mobile phone lies along the principal axis of a concave mirror, as shown in Fig 9
9
163-166
Example 9 2 A mobile phone lies along the principal axis of a concave mirror, as shown in Fig 9 7
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164-167
2 A mobile phone lies along the principal axis of a concave mirror, as shown in Fig 9 7 Show by suitable diagram, the formation of its image
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165-168
9 7 Show by suitable diagram, the formation of its image Explain why the magnification is not uniform
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166-169
7 Show by suitable diagram, the formation of its image Explain why the magnification is not uniform Will the distortion of image depend on the location of the phone with respect to the mirror
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167-170
Show by suitable diagram, the formation of its image Explain why the magnification is not uniform Will the distortion of image depend on the location of the phone with respect to the mirror FIGURE 9
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168-171
Explain why the magnification is not uniform Will the distortion of image depend on the location of the phone with respect to the mirror FIGURE 9 7 EXAMPLE 9
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169-172
Will the distortion of image depend on the location of the phone with respect to the mirror FIGURE 9 7 EXAMPLE 9 2 Rationalised 2023-24 Ray Optics and Optical Instruments 227 EXAMPLE 9
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170-173
FIGURE 9 7 EXAMPLE 9 2 Rationalised 2023-24 Ray Optics and Optical Instruments 227 EXAMPLE 9 3 EXAMPLE 9
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171-174
7 EXAMPLE 9 2 Rationalised 2023-24 Ray Optics and Optical Instruments 227 EXAMPLE 9 3 EXAMPLE 9 4 Solution The ray diagram for the formation of the image of the phone is shown in Fig
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172-175
2 Rationalised 2023-24 Ray Optics and Optical Instruments 227 EXAMPLE 9 3 EXAMPLE 9 4 Solution The ray diagram for the formation of the image of the phone is shown in Fig 9
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173-176
3 EXAMPLE 9 4 Solution The ray diagram for the formation of the image of the phone is shown in Fig 9 7
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174-177
4 Solution The ray diagram for the formation of the image of the phone is shown in Fig 9 7 The image of the part which is on the plane perpendicular to principal axis will be on the same plane
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175-178
9 7 The image of the part which is on the plane perpendicular to principal axis will be on the same plane It will be of the same size, i
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176-179
7 The image of the part which is on the plane perpendicular to principal axis will be on the same plane It will be of the same size, i e
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177-180
The image of the part which is on the plane perpendicular to principal axis will be on the same plane It will be of the same size, i e , BΒ’C = BC
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178-181
It will be of the same size, i e , BΒ’C = BC You can yourself realise why the image is distorted
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179-182
e , BΒ’C = BC You can yourself realise why the image is distorted Example 9
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180-183
, BΒ’C = BC You can yourself realise why the image is distorted Example 9 3 An object is placed at (i) 10 cm, (ii) 5 cm in front of a concave mirror of radius of curvature 15 cm
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181-184
You can yourself realise why the image is distorted Example 9 3 An object is placed at (i) 10 cm, (ii) 5 cm in front of a concave mirror of radius of curvature 15 cm Find the position, nature, and magnification of the image in each case
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182-185
Example 9 3 An object is placed at (i) 10 cm, (ii) 5 cm in front of a concave mirror of radius of curvature 15 cm Find the position, nature, and magnification of the image in each case Solution The focal length f = –15/2 cm = –7
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183-186
3 An object is placed at (i) 10 cm, (ii) 5 cm in front of a concave mirror of radius of curvature 15 cm Find the position, nature, and magnification of the image in each case Solution The focal length f = –15/2 cm = –7 5 cm (i) The object distance u = –10 cm
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184-187
Find the position, nature, and magnification of the image in each case Solution The focal length f = –15/2 cm = –7 5 cm (i) The object distance u = –10 cm Then Eq
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185-188
Solution The focal length f = –15/2 cm = –7 5 cm (i) The object distance u = –10 cm Then Eq (9
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186-189
5 cm (i) The object distance u = –10 cm Then Eq (9 7) gives – –
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187-190
Then Eq (9 7) gives – – 1 1 1 10 7 5 v + = or
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188-191
(9 7) gives – – 1 1 1 10 7 5 v + = or 10 7 5 2 5 v βˆ’Γ— = = – 30 cm The image is 30 cm from the mirror on the same side as the object
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189-192
7) gives – – 1 1 1 10 7 5 v + = or 10 7 5 2 5 v βˆ’Γ— = = – 30 cm The image is 30 cm from the mirror on the same side as the object Also, magnification m = ( 30) – – – 3 ( 10) v u βˆ’ = = βˆ’ The image is magnified, real and inverted
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190-193
1 1 1 10 7 5 v + = or 10 7 5 2 5 v βˆ’Γ— = = – 30 cm The image is 30 cm from the mirror on the same side as the object Also, magnification m = ( 30) – – – 3 ( 10) v u βˆ’ = = βˆ’ The image is magnified, real and inverted (ii) The object distance u = –5 cm
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191-194
10 7 5 2 5 v βˆ’Γ— = = – 30 cm The image is 30 cm from the mirror on the same side as the object Also, magnification m = ( 30) – – – 3 ( 10) v u βˆ’ = = βˆ’ The image is magnified, real and inverted (ii) The object distance u = –5 cm Then from Eq
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192-195
Also, magnification m = ( 30) – – – 3 ( 10) v u βˆ’ = = βˆ’ The image is magnified, real and inverted (ii) The object distance u = –5 cm Then from Eq (9
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193-196
(ii) The object distance u = –5 cm Then from Eq (9 7), 1 1 1 5 7
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194-197
Then from Eq (9 7), 1 1 1 5 7 5 v + = βˆ’ βˆ’ or ( )
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195-198
(9 7), 1 1 1 5 7 5 v + = βˆ’ βˆ’ or ( ) – 5 7 5 15 cm 7 5 5 v Γ— = = This image is formed at 15 cm behind the mirror
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196-199
7), 1 1 1 5 7 5 v + = βˆ’ βˆ’ or ( ) – 5 7 5 15 cm 7 5 5 v Γ— = = This image is formed at 15 cm behind the mirror It is a virtual image
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197-200
5 v + = βˆ’ βˆ’ or ( ) – 5 7 5 15 cm 7 5 5 v Γ— = = This image is formed at 15 cm behind the mirror It is a virtual image Magnification m = 15 – – 3 ( 5) v u = = βˆ’ The image is magnified, virtual and erect
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198-201
– 5 7 5 15 cm 7 5 5 v Γ— = = This image is formed at 15 cm behind the mirror It is a virtual image Magnification m = 15 – – 3 ( 5) v u = = βˆ’ The image is magnified, virtual and erect Example 9
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199-202
It is a virtual image Magnification m = 15 – – 3 ( 5) v u = = βˆ’ The image is magnified, virtual and erect Example 9 4 Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of R = 2 m
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200-203
Magnification m = 15 – – 3 ( 5) v u = = βˆ’ The image is magnified, virtual and erect Example 9 4 Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of R = 2 m If the jogger is running at a speed of 5 m s–1, how fast the image of the jogger appear to move when the jogger is (a) 39 m, (b) 29 m, (c) 19 m, and (d) 9 m away
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201-204
Example 9 4 Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of R = 2 m If the jogger is running at a speed of 5 m s–1, how fast the image of the jogger appear to move when the jogger is (a) 39 m, (b) 29 m, (c) 19 m, and (d) 9 m away Solution From the mirror equation, Eq
9
202-205
4 Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of R = 2 m If the jogger is running at a speed of 5 m s–1, how fast the image of the jogger appear to move when the jogger is (a) 39 m, (b) 29 m, (c) 19 m, and (d) 9 m away Solution From the mirror equation, Eq (9
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203-206
If the jogger is running at a speed of 5 m s–1, how fast the image of the jogger appear to move when the jogger is (a) 39 m, (b) 29 m, (c) 19 m, and (d) 9 m away Solution From the mirror equation, Eq (9 7), we get fu v u f = βˆ’ For convex mirror, since R = 2 m, f = 1 m
9
204-207
Solution From the mirror equation, Eq (9 7), we get fu v u f = βˆ’ For convex mirror, since R = 2 m, f = 1 m Then for u = –39 m, ( 39) 1 39 m 39 1 40 v βˆ’ Γ— = = βˆ’ βˆ’ Since the jogger moves at a constant speed of 5 m s–1, after 1 s the position of the image v (for u = –39 + 5 = –34) is (34/35 )m
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205-208
(9 7), we get fu v u f = βˆ’ For convex mirror, since R = 2 m, f = 1 m Then for u = –39 m, ( 39) 1 39 m 39 1 40 v βˆ’ Γ— = = βˆ’ βˆ’ Since the jogger moves at a constant speed of 5 m s–1, after 1 s the position of the image v (for u = –39 + 5 = –34) is (34/35 )m EXAMPLE 9
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206-209
7), we get fu v u f = βˆ’ For convex mirror, since R = 2 m, f = 1 m Then for u = –39 m, ( 39) 1 39 m 39 1 40 v βˆ’ Γ— = = βˆ’ βˆ’ Since the jogger moves at a constant speed of 5 m s–1, after 1 s the position of the image v (for u = –39 + 5 = –34) is (34/35 )m EXAMPLE 9 2 Rationalised 2023-24 Physics 228 EXAMPLE 9
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207-210
Then for u = –39 m, ( 39) 1 39 m 39 1 40 v βˆ’ Γ— = = βˆ’ βˆ’ Since the jogger moves at a constant speed of 5 m s–1, after 1 s the position of the image v (for u = –39 + 5 = –34) is (34/35 )m EXAMPLE 9 2 Rationalised 2023-24 Physics 228 EXAMPLE 9 4 FIGURE 9
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208-211
EXAMPLE 9 2 Rationalised 2023-24 Physics 228 EXAMPLE 9 4 FIGURE 9 8 Refraction and reflection of light
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209-212
2 Rationalised 2023-24 Physics 228 EXAMPLE 9 4 FIGURE 9 8 Refraction and reflection of light The shift in the position of image in 1 s is 1365 1360 39 34 5 1 m 40 35 1400 1400 280 βˆ’ βˆ’ = = = Therefore, the average speed of the image when the jogger is between 39 m and 34 m from the mirror, is (1/280) m s–1 Similarly, it can be seen that for u = –29 m, –19 m and –9 m, the speed with which the image appears to move is –1 –1 –1 1 1 1 m s , m s and m s , 150 60 10 respectively
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210-213
4 FIGURE 9 8 Refraction and reflection of light The shift in the position of image in 1 s is 1365 1360 39 34 5 1 m 40 35 1400 1400 280 βˆ’ βˆ’ = = = Therefore, the average speed of the image when the jogger is between 39 m and 34 m from the mirror, is (1/280) m s–1 Similarly, it can be seen that for u = –29 m, –19 m and –9 m, the speed with which the image appears to move is –1 –1 –1 1 1 1 m s , m s and m s , 150 60 10 respectively Although the jogger has been moving with a constant speed, the speed of his/her image appears to increase substantially as he/she moves closer to the mirror
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211-214
8 Refraction and reflection of light The shift in the position of image in 1 s is 1365 1360 39 34 5 1 m 40 35 1400 1400 280 βˆ’ βˆ’ = = = Therefore, the average speed of the image when the jogger is between 39 m and 34 m from the mirror, is (1/280) m s–1 Similarly, it can be seen that for u = –29 m, –19 m and –9 m, the speed with which the image appears to move is –1 –1 –1 1 1 1 m s , m s and m s , 150 60 10 respectively Although the jogger has been moving with a constant speed, the speed of his/her image appears to increase substantially as he/she moves closer to the mirror This phenomenon can be noticed by any person sitting in a stationary car or a bus
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212-215
The shift in the position of image in 1 s is 1365 1360 39 34 5 1 m 40 35 1400 1400 280 βˆ’ βˆ’ = = = Therefore, the average speed of the image when the jogger is between 39 m and 34 m from the mirror, is (1/280) m s–1 Similarly, it can be seen that for u = –29 m, –19 m and –9 m, the speed with which the image appears to move is –1 –1 –1 1 1 1 m s , m s and m s , 150 60 10 respectively Although the jogger has been moving with a constant speed, the speed of his/her image appears to increase substantially as he/she moves closer to the mirror This phenomenon can be noticed by any person sitting in a stationary car or a bus In case of moving vehicles, a similar phenomenon could be observed if the vehicle in the rear is moving closer with a constant speed
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213-216
Although the jogger has been moving with a constant speed, the speed of his/her image appears to increase substantially as he/she moves closer to the mirror This phenomenon can be noticed by any person sitting in a stationary car or a bus In case of moving vehicles, a similar phenomenon could be observed if the vehicle in the rear is moving closer with a constant speed 9
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214-217
This phenomenon can be noticed by any person sitting in a stationary car or a bus In case of moving vehicles, a similar phenomenon could be observed if the vehicle in the rear is moving closer with a constant speed 9 3 REFRACTION When a beam of light encounters another transparent medium, a part of light gets reflected back into the first medium while the rest enters the other
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215-218
In case of moving vehicles, a similar phenomenon could be observed if the vehicle in the rear is moving closer with a constant speed 9 3 REFRACTION When a beam of light encounters another transparent medium, a part of light gets reflected back into the first medium while the rest enters the other A ray of light represents a beam
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216-219
9 3 REFRACTION When a beam of light encounters another transparent medium, a part of light gets reflected back into the first medium while the rest enters the other A ray of light represents a beam The direction of propagation of an obliquely incident (0Β°< i < 90Β°) ray of light that enters the other medium, changes at the interface of the two media
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217-220
3 REFRACTION When a beam of light encounters another transparent medium, a part of light gets reflected back into the first medium while the rest enters the other A ray of light represents a beam The direction of propagation of an obliquely incident (0Β°< i < 90Β°) ray of light that enters the other medium, changes at the interface of the two media This phenomenon is called refraction of light
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218-221
A ray of light represents a beam The direction of propagation of an obliquely incident (0Β°< i < 90Β°) ray of light that enters the other medium, changes at the interface of the two media This phenomenon is called refraction of light Snell experimentally obtained the following laws of refraction: (i) The incident ray, the refracted ray and the normal to the interface at the point of incidence, all lie in the same plane
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219-222
The direction of propagation of an obliquely incident (0Β°< i < 90Β°) ray of light that enters the other medium, changes at the interface of the two media This phenomenon is called refraction of light Snell experimentally obtained the following laws of refraction: (i) The incident ray, the refracted ray and the normal to the interface at the point of incidence, all lie in the same plane (ii) The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant
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220-223
This phenomenon is called refraction of light Snell experimentally obtained the following laws of refraction: (i) The incident ray, the refracted ray and the normal to the interface at the point of incidence, all lie in the same plane (ii) The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant Remember that the angles of incidence (i ) and refraction (r ) are the angles that the incident and its refracted ray make with the normal, respectively
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221-224
Snell experimentally obtained the following laws of refraction: (i) The incident ray, the refracted ray and the normal to the interface at the point of incidence, all lie in the same plane (ii) The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant Remember that the angles of incidence (i ) and refraction (r ) are the angles that the incident and its refracted ray make with the normal, respectively We have 21 sin sin i r =n (9
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222-225
(ii) The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant Remember that the angles of incidence (i ) and refraction (r ) are the angles that the incident and its refracted ray make with the normal, respectively We have 21 sin sin i r =n (9 10) where n 21 is a constant, called the refractive index of the second medium with respect to the first medium
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223-226
Remember that the angles of incidence (i ) and refraction (r ) are the angles that the incident and its refracted ray make with the normal, respectively We have 21 sin sin i r =n (9 10) where n 21 is a constant, called the refractive index of the second medium with respect to the first medium Equation (9
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224-227
We have 21 sin sin i r =n (9 10) where n 21 is a constant, called the refractive index of the second medium with respect to the first medium Equation (9 10) is the well-known Snell’s law of refraction
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225-228
10) where n 21 is a constant, called the refractive index of the second medium with respect to the first medium Equation (9 10) is the well-known Snell’s law of refraction We note that n 21 is a characteristic of the pair of media (and also depends on the wavelength of light), but is independent of the angle of incidence
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226-229
Equation (9 10) is the well-known Snell’s law of refraction We note that n 21 is a characteristic of the pair of media (and also depends on the wavelength of light), but is independent of the angle of incidence From Eq
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227-230
10) is the well-known Snell’s law of refraction We note that n 21 is a characteristic of the pair of media (and also depends on the wavelength of light), but is independent of the angle of incidence From Eq (9
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228-231
We note that n 21 is a characteristic of the pair of media (and also depends on the wavelength of light), but is independent of the angle of incidence From Eq (9 10), if n 21 > 1, r < i, i
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229-232
From Eq (9 10), if n 21 > 1, r < i, i e
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230-233
(9 10), if n 21 > 1, r < i, i e , the refracted ray bends towards the normal
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231-234
10), if n 21 > 1, r < i, i e , the refracted ray bends towards the normal In such a case medium 2 is said to be optically denser (or denser, in short) than medium 1
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232-235
e , the refracted ray bends towards the normal In such a case medium 2 is said to be optically denser (or denser, in short) than medium 1 On the other hand, if n 21 <1, r > i, the Rationalised 2023-24 Ray Optics and Optical Instruments 229 refracted ray bends away from the normal
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233-236
, the refracted ray bends towards the normal In such a case medium 2 is said to be optically denser (or denser, in short) than medium 1 On the other hand, if n 21 <1, r > i, the Rationalised 2023-24 Ray Optics and Optical Instruments 229 refracted ray bends away from the normal This is the case when incident ray in a denser medium refracts into a rarer medium
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234-237
In such a case medium 2 is said to be optically denser (or denser, in short) than medium 1 On the other hand, if n 21 <1, r > i, the Rationalised 2023-24 Ray Optics and Optical Instruments 229 refracted ray bends away from the normal This is the case when incident ray in a denser medium refracts into a rarer medium Note: Optical density should not be confused with mass density, which is mass per unit volume
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235-238
On the other hand, if n 21 <1, r > i, the Rationalised 2023-24 Ray Optics and Optical Instruments 229 refracted ray bends away from the normal This is the case when incident ray in a denser medium refracts into a rarer medium Note: Optical density should not be confused with mass density, which is mass per unit volume It is possible that mass density of an optically denser medium may be less than that of an optically rarer medium (optical density is the ratio of the speed of light in two media)
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236-239
This is the case when incident ray in a denser medium refracts into a rarer medium Note: Optical density should not be confused with mass density, which is mass per unit volume It is possible that mass density of an optically denser medium may be less than that of an optically rarer medium (optical density is the ratio of the speed of light in two media) For example, turpentine and water
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237-240
Note: Optical density should not be confused with mass density, which is mass per unit volume It is possible that mass density of an optically denser medium may be less than that of an optically rarer medium (optical density is the ratio of the speed of light in two media) For example, turpentine and water Mass density of turpentine is less than that of water but its optical density is higher
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238-241
It is possible that mass density of an optically denser medium may be less than that of an optically rarer medium (optical density is the ratio of the speed of light in two media) For example, turpentine and water Mass density of turpentine is less than that of water but its optical density is higher If n 21 is the refractive index of medium 2 with respect to medium 1 and n12 the refractive index of medium 1 with respect to medium 2, then it should be clear that 12 21 1 n =n (9