The length of a telescope, for which it is known that it has an objective lens of focal length 144 cm and an eye piece of focal length 6 cm is

Options

A. 1.5m
B. 1.44m
C. 1.38m
D. 1.56 m

Answer

To find the length of the telescope, we need to use the formula that relates the focal lengths of the objective lens and the eyepiece.

### Step-by-step Solution:

1. **Identify the Focal Lengths**:
- The focal length of the objective lens (\(f_o\)) is given as 144 cm.
- The focal length of the eyepiece (\(f_e\)) is given as 6 cm.

2. **Use the Formula for Length of Telescope**:
- The length of the telescope (\(L\)) is given by the sum of the focal lengths of the objective and the eyepiece:
\[ L = f_o + f_e \]

3. **Substitute the Values**:
- Substitute the values of \(f_o\) and \(f_e\) into the formula:
\[ L = 144 \, \text{cm} + 6 \, \text{cm} \]

4. **Calculate the Length**:
- Perform the addition:
\[ L = 150 \, \text{cm} \]

5. **Convert to Meters (if necessary)**:
- Since 1 meter = 100 cm, we can convert 150 cm to meters:
\[ L = 1.5 \, \text{m} \]

### Final Answer:
The length of the telescope is **1.5 meters**.

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