Question

For an astronomical telescope having objective lens of focal length 10 m and eyepiece lens of focal length 10 cm, telescope’s the tube length and magnification respectively are __________.
.Fill in the blank with the correct answer from the options given below.

• A. 20 cm, 1
• B. 1000 cm, 1
• C. 1010 cm, 1
• D. 1010 cm, 100

Answer 1

The Correct Option is D

An astronomical telescope uses two lenses: the objective lens and the eyepiece lens. The tube length of the telescope is the sum of the focal lengths of these two lenses. Given:
Focal length of the objective lens, \( f_o = 10 \, \text{m} = 1000 \, \text{cm} \)
Focal length of the eyepiece lens, \( f_e = 10 \, \text{cm} \)
Tube length, \( L \), is given by:

\( L = f_o + f_e \)

Substituting the values:

\( L = 1000 \, \text{cm} + 10 \, \text{cm} = 1010 \, \text{cm} \)

Now, to find the magnification \( M \), we use the formula:

\( M = \frac{f_o}{f_e} \)

Substituting the given values:

\( M = \frac{1000 \, \text{cm}}{10 \, \text{cm}} = 100 \)

Thus, the tube length is 1010 cm, and the magnification is 100. Therefore, the correct answer is: 1010 cm, 100

Answer 2

Let's analyze the astronomical telescope and calculate its tube length and magnification.

1. Given Values:

• Focal length of objective lens (f_o) = 10 m = 1000 cm
• Focal length of eyepiece lens (f_e) = 10 cm

2. Tube Length (L):

The tube length of an astronomical telescope is the sum of the focal lengths of the objective and eyepiece lenses:

L = f_o + f_e

L = 1000 cm + 10 cm

L = 1010 cm

3. Magnification (M):

The magnification of an astronomical telescope is given by:

M = f_o / f_e

M = 1000 cm / 10 cm

M = 100

Therefore, the tube length is 1010 cm, and the magnification is 100.

The correct answer is:

Option 4: 1010 cm, 100