Test Index

JAMB Physics 2019 Paper

Question : 19

Total: 100

Solution:

Concept:

A current-carrying wire in a magnetic field experiences a force given by the motor rule formula.

Explanation:

The force on the wire is calculated using

F = BIL\sin\theta

The wire is at a right angle to the field, so

\theta = 90^\circ

and

\sin 90^\circ = 1

Convert the length from cm to m:

L = 15\text{ cm} = 0.15\text{ m}

Substitute the values:

B = 0.40\text{ T}

I = 6.0\text{ A}

L = 0.15\text{ m}

Thus,

F = 0.40 \times 6.0 \times 0.15

F = 0.36\text{ N}

Answer:

The force on the wire is

0.36\text{ N}

, so the correct option is C.

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