A wire of length 2 m carrying 4 A is placed in a 0.5 T field at 30 degrees to the field lines. What force acts on it?
Answer and explanation
Correct answer: B. 2 N
- Step 1: The force on a current-carrying wire is F = B I L sin(theta).
- Step 2: F = 0.5 x 4 x 2 x sin(30) = 2 N.
Answer
2 N.
Why not the others: '4 N' uses sin(90) = 1 instead of sin(30) = 1/2; '8 N' omits the field strength and the sine of the angle; '1 N' halves the force twice.
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