Question

The frequency of sinusodial wave y = 0.40cos [2000 t + 0.80] would be

• A. $1000\, \pi \,Hz$
• B. $2000 \,Hz$
• C. $20\, Hz$
• D. $\frac{1000}{\pi} \,Hz$

Answer 1

Answer: (D)

$\frac{1000}{\pi} \,Hz$

Answer 2

Compare with the equation
$y=a \cos(2\pi \upsilon t+ \phi)$
This give $2\pi \upsilon =2000$
$\upsilon=\frac{1000}{\pi}\,Hz$