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WAEC Physics 2013 Paper

Question : 21

Total: 46

\pi \left( \; \frac{t}{0.01} - \; \frac{x}{30} \right)

Solution:

Concept:

A progressive transverse wave is expressed as

y = A \sin 2\pi \left( \frac{t}{T} - \frac{x}{\lambda} \right)

Here,

T

is the period and

\lambda

is the wavelength.

Explanation:

The given wave equation is:

y = 2 \sin 2\pi \left( \frac{t}{0.01} - \frac{x}{30} \right)

Compare this with the standard wave equation:

y = A \sin 2\pi \left( \frac{t}{T} - \frac{x}{\lambda} \right)

The coefficient of

t

inside the bracket gives:

\frac{t}{T} = \frac{t}{0.01}

Cancelling

t

from both sides:

\frac{1}{T} = \frac{1}{0.01}

Therefore, the period is:

T = 0.01 \, \text{s} = 0.010 \, \text{s}

Answer:

T = 0.010 \, \text{s}

, so the correct option is B.

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