Waves - Result Question 31

31. The frequency of sinusoidal wave $y=0.40 \cos$ $[2000 t+0.80]$ would be

[1992]

(a) $1000 \pi Hz$

(b) $2000 Hz$

(c) $20 Hz$

(d) $\frac{1000}{\pi} Hz$

Show Answer

Answer:

Correct Answer: 31. (d)

Solution:

  1. (d) Given $y=0.40 \cos [2000 t+0.80]$

Comparing with the standard equation

$y=A \cos (2 \pi v t+\phi)$

We get angular frequency, $2 \pi \nu=2000$ $v \Rightarrow \frac{2000}{2 \pi}=\frac{1000}{\pi} Hz$