D. is the correct answer.
Explanation:
★A compound pendulum has an extended mass, like a swinging bar, and is free to oscillate about a horizontal axis. A special reversible compound pendulum called Kater’s pendulum is designed to measure the value of g, the acceleration of gravity.
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Answer:
Answer is C because light travels in a sight line but when light pass through a refractor the light from the source changes direction when passes through a refractor
