Q. No.The earth takes \(24~\text{h}\) to rotate once about its axis. How much time does the sun take to shift by \(1^{\circ}\) when viewed from the earth?
1. \(3~\text{minutes}\)
2. \(2~\text{minutes}\)
3. \(1~\text{minutes}\)
4. \(4~\text{minutes}\)
1. \(3~\text{minutes}\)
2. \(2~\text{minutes}\)
3. \(1~\text{minutes}\)
4. \(4~\text{minutes}\)
Light from a point source in the air falls on a convex spherical glass surface (n = 1.5 and radius of curvature = 20 cm) of a glass medium which extends till infinity on other side . The distance of the light source from the glass surface is 100 cm. At what position the image is formed?
| 1. | at a distance of 200 cm from the glass surface, in the direction of incident light. |
| 2. | at a distance of 100 cm from the glass surface, in the direction of incident light. |
| 3. | at a distance of 200 cm from the glass surface, in the opposite direction of incident light. |
| 4. | at a distance of 100 cm from the glass surface, in the opposite direction of incident light. |
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. \( 1.5\)
If \(f=0.5~\text m\) for a glass lens, what is the power of the lens?
1. \(+0.4~\text D\)
2. \(+4.0~\text D\)
3. \(+0.2~\text D\)
4. \(+2.0~\text D\)
The radii of curvature of the faces of a double convex lens are \(10\) cm and \(15\) cm. Its focal length is \(12\) cm. What is the refractive index of glass?
1. \(1.3\)
2. \(1.2\)
3. \(1.5\)
4. \(1.4\)
A convex lens has a \(20~\text{cm}\) focal length in air. What is the focal length in water?
(the refractive index of air-water \(=1.33,\) refractive index for air-glass \(=1.5\))
1. \(+72.72~\text{cm}\)
2. \(+78.2~\text{cm}\)
3. \(-72.72~\text{cm}\)
4. \(+70.2~\text{cm}\)
Find the position of the image formed by the lens combination in the given figure.
The final image is:
| 1. | formed \( 30 ~\text{cm} \) to the right of the third lens. |
| 2. | formed \(20 ~\text{cm} \) to the left of the third lens. |
| 3. | formed \( 30 ~\text{cm} \) to the left of the third lens. |
| 4. | formed \(20 ~\text{cm} \) to the right of the third lens. |
What focal length should the reading spectacles have for a person for whom the least distance of distinct vision is \(50~\text{cm}\)?
1. \(-50~\text{cm}\)
2. \(+50~\text{cm}\)
3. \(-60~\text{cm}\)
4. \(+60~\text{cm}\)
The far point of a myopic person is \(80~\text{cm}\) in front of the eye. What is the power of the lens required to enable him to see very distant objects clearly?
1. \(-1.25~\text{D}\)
2. \(+1.25~\text{D}\)
3. \(-2.12~\text{D}\)
4. \(+2.12~\text{D}\)
The near point of a hypermetropic person is \(75~\text{cm}\) from the eye. What is the power of the lens required to enable the person to read clearly a book held at \(25~\text{cm}\) from the eye?
1. \(+2.67~\text{D}\)
2. \(-1.25~\text{D}\)
3. \(-2.67~\text{D}\)
4. \(+1.25~\text{D}\)
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