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Q. No.A telescope has an objective lens of focal length \(150~\text{cm}\) and an eyepiece of focal length \(5~\text{cm}.\) If a \(50~\text{m}\) tall tower at a distance of \(1~\text{km}\) is observed through this telescope in a normal setting, the angle formed by the image of the tower is \(\theta,\) and \(\theta\) is close to:
1. \(15^\circ\)
2. \(60^\circ\)
3. \(30^\circ\)
4. \(18^\circ\)
1. \(15^\circ\)
2. \(60^\circ\)
3. \(30^\circ\)
4. \(18^\circ\)
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An observer looks at a distant tree of height \(10~\text{m}\) with a telescope of magnifying power of \(20\). To the observer, the tree appears:
| 1. | \(10\) times taller |
| 2. | \(10\) times nearer |
| 3. | \(20\) times taller |
| 4. | \(20\) times nearer |
Subtopic: Telescope |
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A compound microscope consists of an objective lens of focal length \(1~\text{cm}\) and an eye piece of focal length \(5~\text{cm}\) with a separation of \(10~\text{cm}\). The distance between an object and the objective lens, at which the strain on the eye is minimum is \(\frac{n}{40}~\text{cm}\). The value of \(n\) is:
1. \(100\)
2. \(50\)
3. \(25\)
4. \(10\)
Subtopic: Telescope |
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In normal adjustment, for a refracting telescope, the distance between the objective and eyepiece is \(30\) cm. The focal length of the objective, when the angular magnification of the telescope is \(2,\) will be:
1. \(20\) cm
2. \(30\) cm
3. \(10\) cm
4. \(15\) cm
1. \(20\) cm
2. \(30\) cm
3. \(10\) cm
4. \(15\) cm
Subtopic: Telescope |
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Two different lenses are used in telescope because:
1. Magnification is increased
2. Focal length is increased
3. More light is captured
4. Spherical aberration is increased
1. Magnification is increased
2. Focal length is increased
3. More light is captured
4. Spherical aberration is increased
Subtopic: Telescope |
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A telescope has a tube length of \(60 ~\text{cm}\) and a magnifying power of \(5 .\) What is the focal length of its eyepiece?
| 1. | \(40 ~\text{cm}\) | 2. | \(10 ~\text{cm}\) |
| 3. | \(20 ~\text{cm}\) | 4. | \(30 ~\text{cm}\) |
Subtopic: Telescope |
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Two stars are \(10\) light years away from the Earth. They are seen through a telescope of objective diameter \(30~\text{cm.}\) The wavelength of light \(600~\text{nm}.\) To see the stars just resolved by the telescope, the minimum distance between them should be (\(1\) light year \(= 9.46 × 10^{15}~\text{m}\) ) the order of:
1. \(10^8~\text{km}\)
2. \(10^6~\text{km}\)
3. \(10^{11}~\text{km}\)
4. \(10^{10}~\text{km}\)
1. \(10^8~\text{km}\)
2. \(10^6~\text{km}\)
3. \(10^{11}~\text{km}\)
4. \(10^{10}~\text{km}\)
Subtopic: Telescope |
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