A convex lens is used to form image of an object on screen. When half of the lens is covered by painting black on it, then

Options

A. Intensity of the image formed will remain same
B. Intensity of the image formed will decrease
C. Half of the image will be formed on the screen
D. Complete image will be formed on the screen

Explanation

To solve the problem of what happens when half of a convex lens is covered, we can follow these steps:

### Step 1: Understand the Function of a Convex Lens
A convex lens converges light rays that pass through it to form an image on the opposite side. When the lens is fully functional, all light rays from an object can pass through and contribute to the image formation.

**Hint:** Remember that a convex lens focuses light rays to a point called the focus.

### Step 2: Analyze the Effect of Covering Half of the Lens
When half of the lens is covered (painted black), it blocks light from passing through that portion. This means that only the uncovered half of the lens can contribute to the image formation.

**Hint:** Consider how many light rays can pass through the lens when it is partially covered.

### Step 3: Determine the Image Formation
Even though half of the lens is covered, the rays that pass through the uncovered part can still converge to form an image. The image will still be complete because the rays that pass through the optical center of the lens will still meet at the same focal point.

**Hint:** Visualize the path of light rays through the lens to see how they converge.

### Step 4: Assess the Brightness of the Image
While the image is complete, the intensity (brightness) of the image will decrease. This is because only half of the light rays are contributing to the image formation. The intensity of the image is proportional to the amount of light that reaches the screen.

**Hint:** Think about how the brightness of an image changes with the amount of light available.

### Step 5: Conclusion
The final conclusion is that when half of the convex lens is covered, a complete image is still formed on the screen, but the intensity (brightness) of that image decreases.

**Final Answer:** The complete image will be formed, but the intensity of the image will decrease.

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