Answer:
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B. Switch</h2>
Explanation:
<u>A device designed to open or close a circuit under controlled conditions is called a switch. The terms “open” and “closed” refer to switches as well as entire circuits. An open switch is one without continuity: current cannot flow through it.</u>
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Answer: D Although the total energy remains constant, nonrenewable fuels convert chemical energy into forms that are difficult or impossible to use again.
Explanation:
The first law of thermodynamics says that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another.
Answer:

Given:
Force = 8 N
Distance covered by the body = 50 cm = 0.5 m
Explanation:
Work Done = Force × Distance covered by the body
= 8 × 0.5
= 4 J