To find the focal length of a convex lens, an image of a far located tree is obtained on a screen. For this the distance measured is:

Options

A. Only of between screen and tree
B. Only of between lens and screen
C. Only of between lens and tree
D. Between screen and tree and lens & screen

Explanation

To find the focal length of a convex lens using the image of a far-located tree, follow these steps:

### Step 1: Set Up the Experiment
- Place the convex lens on a stable surface.
- Position a screen on the opposite side of the lens where the image will be formed.

### Step 2: Position the Tree
- Ensure that the tree is located at a significant distance (considered to be at infinity for practical purposes) from the lens. This means the rays coming from the tree are nearly parallel when they reach the lens.

### Step 3: Focus the Image
- Adjust the position of the screen until a clear image of the tree is formed on the screen. Since the tree is far away, the image will be formed at the focal point of the lens.

### Step 4: Measure the Distance
- Measure the distance between the lens and the screen. This distance corresponds to the focal length of the lens when the object is at infinity.

### Step 5: Record the Focal Length
- The measured distance from the lens to the screen is the focal length of the convex lens.

### Final Answer
- The correct option for the distance measured to find the focal length of the convex lens is the distance between the lens and the screen.

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