Assertion : Optical fibres make use of total internal reflection.
Reason : Light undergoes successive total internal reflections as it moves through an optical fibre.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true and reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the assertion and reason question regarding optical fibers and total internal reflection, we can break it down into the following steps:

### Step 1: Understand the Assertion
The assertion states that "Optical fibers make use of total internal reflection."
- **Explanation**: Optical fibers are designed to transmit light over long distances. They rely on the principle of total internal reflection to keep the light confined within the core of the fiber, allowing it to travel without significant loss.

### Step 2: Understand the Reason
The reason states that "Light undergoes successive total internal reflections as it moves through an optical fiber."
- **Explanation**: As light enters the optical fiber, it hits the boundary between the core and the cladding at an angle greater than the critical angle. This causes the light to reflect back into the core repeatedly, allowing it to travel through the fiber.

### Step 3: Evaluate the Truth of the Assertion and Reason
- **Assertion**: True. Optical fibers indeed utilize total internal reflection.
- **Reason**: True. Light does undergo successive total internal reflections as it travels through the optical fiber.

### Step 4: Determine the Relationship Between Assertion and Reason
- The assertion is true, and the reason is also true. However, the reason does not provide a correct explanation for the assertion. The assertion is about the use of total internal reflection in optical fibers, while the reason describes the behavior of light within the fiber.

### Conclusion
Based on the evaluation:
- Both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer
The correct option is: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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