Two convex lenses of focal lengths `0.3m` and `0.05m` are used to make a telescope. The distance kept between the two is

Options

A. `0.35m`
B. `0.25m`
C. `0.175 m`
D. `0.15m`

Explanation

To solve the problem of determining the distance between two convex lenses used to make a telescope, we can follow these steps:

### Step 1: Identify the focal lengths of the lenses
We have two convex lenses with the following focal lengths:
- Focal length of the objective lens (FO) = 0.3 m
- Focal length of the eyepiece lens (FE) = 0.05 m

### Step 2: Understand the configuration of the telescope
In a telescope, the objective lens is used to gather light and form an image, while the eyepiece lens magnifies that image. The objective lens has a longer focal length compared to the eyepiece lens.

### Step 3: Use the formula for the distance between the lenses
The distance (L) between the two lenses in a telescope is given by the sum of the focal lengths of the objective lens and the eyepiece lens:
\[ L = FO + FE \]

### Step 4: Substitute the values into the formula
Now, we can substitute the known values of the focal lengths into the formula:
\[ L = 0.3 \, \text{m} + 0.05 \, \text{m} \]

### Step 5: Perform the calculation
Now we can perform the addition:
\[ L = 0.3 + 0.05 = 0.35 \, \text{m} \]

### Final Answer
The distance kept between the two lenses is **0.35 meters**.

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