Focal length of objective and eye piece of telescope are 200 cm and 4 cm respectively. What is the length of telescope for normal adjustment?

Options

A. 196 cm
B. 204 cm
C. 250 cm
D. 225 cm

Answer

To find the length of the telescope for normal adjustment, we need to consider the focal lengths of the objective and the eyepiece.

### Step-by-Step Solution:

1. **Understand the Concept of Normal Adjustment**:
- In normal adjustment of a telescope, the image formed by the objective lens is at the focal point of the eyepiece lens. This allows the observer to see the image clearly at a distance (far point) without straining their eyes.

2. **Identify the Focal Lengths**:
- The focal length of the objective lens (\(F_o\)) is given as 200 cm.
- The focal length of the eyepiece lens (\(F_e\)) is given as 4 cm.

3. **Determine the Length of the Telescope**:
- The length of the telescope (or tube length) in normal adjustment is the sum of the focal lengths of the objective and the eyepiece:
\[ \text{Length of Telescope} = F_o + F_e \]

4. **Substitute the Values**:
- Substitute the given focal lengths into the equation:
\[ \text{Length of Telescope} = 200 \, \text{cm} + 4 \, \text{cm} = 204 \, \text{cm} \]

5. **Conclusion**:
- Therefore, the length of the telescope for normal adjustment is 204 cm.

### Final Answer:
The length of the telescope for normal adjustment is **204 cm**.

---