Q. No.A point source of light is placed in front of a plane mirror. Choose the correct statement.
| 1. | All the reflected rays meet at a point when produced backward. |
| 2. | Only the reflected rays close to the normal meet at a point when produced backward. |
| 3. | Only the reflected rays making a small angle with the mirror meet at a point when produced backward. |
| 4. | Light of different colours make different images. |
Total internal reflection can take place only if:
| 1. | the light goes from optically rarer medium (smaller refractive index) to optically denser medium. |
| 2. | the light goes from optically denser medium to rarer medium. |
| 3. | the refractive indices of the two media are close to each other. |
| 4. | the refractive indices of the two media are widely different. |
In image formation from spherical mirrors, only paraxial rays are considered because they;
| 1. | are easy to handle geometrically |
| 2. | contain most of the intensity of the incident light |
| 3. | form nearly a point image of a point source |
| 4. | show minimum dispersion effect |
A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. The image will form at
1. infinity
2. pole
3. focus
4. 15 cm behind the mirror
The figure shows two rays A and B being reflected by a mirror and going as A' and B'. The mirror,
1. is plane
2. is convex
3. is concave
4. may be any spherical mirror
The image formed by a concave mirror:
| 1. | is always real |
| 2. | is always virtual |
| 3. | is certainly real if the object is virtual |
| 4. | is certainly virtual if the object is real |
The figure shows three transparent media of refractive indices \(\mu_1,~\mu_2\) and \(\mu_3\). A point object \(O\) is placed in the medium \(\mu_2\). If the entire medium on the right of the spherical surface has refractive index \(\mu_1\), the image forms at \(O'.\) If this entire medium has refractive index \(\mu_3\), the image forms at \(O''.\) In the situation shown,
| 1. | the image forms between \(O'\) and \(O''.\) |
| 2. | the image forms to the left of \(O'.\) |
| 3. | the image forms to the right of \(O''.\) |
| 4. | two images form, one at \(O'\) and the other at \(O''.\) |
Four modifications are suggested in the lens formula to include the effect of the thickness t of the lens. Which one is likely to be correct?
1. \(\frac{1}{v}-\frac{1}{u}=\frac{t}{u f}\)
2. \(\frac{t}{v^{2}}-\frac{1}{u}=\frac{1}{f}\)
3. \(\frac{1}{v-t}-\frac{1}{u+t}=\frac{1}{f}\)
4. \(\frac{1}{v}-\frac{1}{u}+\frac{t}{u v}=\frac{t}{f}\)
A double convex lens has two surfaces of equal radii \(R\) and refractive index \(m=1.5.\) We have:
1. \(f=R/2\)
2. \(f=R \)
3. \(f=-R\)
4. \(f=2R\)
A point source of light is placed at a distance of \(2 f\) from a converging lens of focal length \(f.\) The intensity on the other side of the lens is maximum at a distance:
| 1. | \(f\) | 2. | between \(f\) and \(2 f\) |
| 3. | \(2 f\) | 4. | more than \(2 f\) |
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