Total internal reflection can take place only if

1. light goes from optically rarer medium (smaller refractive index) to optically denser medium

2. 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,

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

3.  more than 2 f

A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from the lens on the other side on its principal axis, the intensity of light

1. remains constant

2. continuously increases

3. continuously decreases

4. first increases then decreases