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JAMB Physics 2012 Paper

Question : 35

Total: 42

Solution:

Concept:

The d.c. equivalent of an alternating current is its root-mean-square (r.m.s.) value.

Explanation:

For a sinusoidal current given as

I = I_0 \sin \omega t

, the r.m.s. value is:

I_{\text{rms}} = \frac{I_0}{\sqrt{2}}

From the equation

I = 10 \sin \omega t

, the peak current is

I_0 = 10 \, \text{A}

Substitute the peak current:

I_{\text{rms}} = \frac{10}{\sqrt{2}} = 7.07 \, \text{A}

Rounding to one decimal place gives

7.1 \, \text{A}

Answer:

7.1 \, \text{A}

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