Find the value of the angle of emergence from the prism given below for the incidence ray shown. The refractive index of the glass is \(\sqrt{3}\).
1. \(45^{\circ}\)
2. \(90^{\circ}\)
3. \(60^{\circ}\)
4. \(30^{\circ}\)
A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:
1. | a large aperture contributes to the quality and visibility of the images. |
2. | a large area of the objective ensures better light-gathering power. |
3. | a large aperture provides a better resolution. |
4. | all of the above. |
A point object is placed at a distance of \(60~\text{cm}\) from a convex lens of focal length \(30~\text{cm}\). If a plane mirror were put perpendicular to the principal axis of the lens and at a distance of \(40~\text{cm}\) from it, the final image would be formed at a distance of:
1. | \(30~\text{cm}\) from the plane mirror, it would be a virtual image. |
2. | \(20~\text{cm}\) from the plane mirror, it would be a virtual image. |
3. | \(20~\text{cm}\) from the lens, it would be a real image. |
4. | \(30~\text{cm}\) from the lens, it would be a real image. |
A magician during a show makes a glass lens with \(n=1.47\) disappear in a trough of liquid. What is the refractive index of the liquid?
1. \( 1.47 \)
2. \( 1.33 \)
3. \(0.66 \)
4. \( 1.5\)
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 |
To increase the angular magnification of a simple microscope, one should increase:
1. | the focal length of the lens | 2. | the power of the lens |
3. | the aperture of the lens | 4. | the object size |
A rod of length \(10~\text{cm}\) lies along the principal axis of a concave mirror of focal length \(10~\text{cm}\) in such a way that its end closer to the pole is \(20~\text{cm}\) away from the mirror. The length of the image is:
1. \(15~\text{cm}\)
2. \(2.5~\text{cm}\)
3. \(5~\text{cm}\)
4. \(10~\text{cm}\)
For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index:
1. | \(2\) and \(\sqrt{2}\) | lies between
2. | \(1\) | is less than
3. | \(2\) | is greater than
4. | \(\sqrt{2}\) and \(1\) | lies between
If the critical angle for total internal reflection from a medium to vacuum is \(45^{\circ}\), the velocity of light in the medium is:
1. | \(1.5\times10^{8}~\text{m/s}\) | 2. | \(\dfrac{3}{\sqrt{2}}\times10^{8}~\text{m/s}\) |
3. | \(\sqrt{2}\times10^{8}~\text{m/s}\) | 4. | \(3\times10^{8}~\text{m/s}\) |