When a thin metal plate is placed in the path of one of the interfering beams of light

Options

A. the fringes become blurred
B. the fringes become brighter
C. the fringes disappear
D. the fringe width increase

Answer

To solve the question, "When a thin metal plate is placed in the path of one of the interfering beams of light, what will happen?", we can analyze the situation step by step.

### Step-by-Step Solution:

1. **Understanding Interference**: In Young's double-slit experiment, two coherent light sources produce an interference pattern on a screen. This pattern consists of alternating bright and dark fringes due to constructive and destructive interference of light waves.

2. **Effect of the Thin Metal Plate**: When a thin metal plate is placed in the path of one of the interfering beams, it will block that beam of light. This means that one of the two light sources contributing to the interference pattern is now obstructed.

3. **Resulting Light Condition**: Since interference requires at least two coherent light waves, the obstruction of one beam means that only one beam of light is reaching the screen.

4. **Conclusion on Fringes**: With only one beam of light present, there can be no interference pattern formed. Therefore, the bright and dark fringes that were previously visible will disappear.

5. **Final Answer**: The correct answer to the question is that the fringes will disappear when a thin metal plate is placed in the path of one of the interfering beams of light.