In an astronomical telescope of refracting type, objective has greater focal length. Explain.

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In an astronomical telescope of refracting type, the objective has a greater focal length because the objective's function is to form a real image of a distant object at its focus. In an astronomical telescope, the objective lens is used to gather the light from distant celestial objects and form a real image at its focus. This real image is then magnified by the eyepiece to form a virtual image.

For a telescope to have a high magnification, the eyepiece must have a short focal length. The magnification of a telescope is given by the ratio of the focal length of the objective to the focal length of the eyepiece. Therefore, to achieve high magnification, the objective should have a greater focal length than the eyepiece.

In addition to this, having a greater focal length also allows for a larger aperture, which means that more light can be gathered by the objective lens. This results in a brighter and sharper image, which is crucial when observing distant celestial objects.

Therefore, to achieve a high magnification and a brighter, sharper image, the objective lens of an astronomical telescope must have a greater focal length.

$Refracting Astronomical Telescope$

Refracting Astronomical Telescope

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CBSE CLASS XII Related Questions

1.
Read the following paragraph and answer the questions that follow.
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2.
The resistance of a metal wire at $ 20^\circ \text{C} $ is $ 1.05 \, \Omega $ and at $ 100^\circ \text{C} $ is $ 1.38 \, \Omega $. Determine the temperature coefficient of resistivity of this metal.

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3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

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Read the following paragraph and answer the questions that follow.
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6.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

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In an astronomical telescope of refracting type, objective has greater focal length. Explain.

CBSE CLASS XII Related Questions

2.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

6.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

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In an astronomical telescope of refracting type, objective has greater focal length. Explain.

CBSE CLASS XII Related Questions

2. The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

3.A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

6.Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

Comments

SUBSCRIBE TO OUR NEWS LETTER

2.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

6.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.