For a telescrope, focal length of objective lens is 15 cm and focal length of eye piece is 10 mm. if tube length is 16 cm, then find the magnification.

Options

A. 150
B. 15
C. 1.5
D. 10

Explanation

To solve the problem of finding the magnification of a telescope given the focal lengths of the objective lens and eyepiece, as well as the tube length, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Focal length of the objective lens (F₀) = 15 cm
- Focal length of the eyepiece (Fₑ) = 10 mm = 1 cm (since 10 mm = 1 cm)
- Tube length (L) = 16 cm

2. **Understand the Formula for Magnification (M):**
The magnification (M) for a telescope can be calculated using the formula:
\[ M = \frac{F₀}{Fₑ} \]
However, since we have the tube length, we need to ensure that we are using the correct formula that incorporates the tube length. The correct formula for magnification in terms of tube length is:
\[ M = \frac{L}{Fₑ} \text{ (for the eyepiece)} \]

3. **Calculate the Magnification:**
- First, we need to convert the focal length of the eyepiece into the same units as the tube length. Since Fₑ is already in cm (1 cm), we can directly use it.
- Now substitute the values into the magnification formula:
\[ M = \frac{L}{Fₑ} = \frac{16 \text{ cm}}{1 \text{ cm}} = 16 \]

4. **Final Magnification Calculation:**
The magnification of the telescope is:
\[ M = 16 \]

### Conclusion:
The magnification of the telescope is 16.