Question

The magnetic field intensity vector of a plane wave is given by

$\overrightarrow{H}(x.t)=10sin(50000t+0.004x+30){\hat{a}}_y$ where ${\hat{a}}_y$ denotes the unit vector in y direction. The wave is propagating with a phase velocity

• A. $3\times {10}^{8}m/s$
• B. $3\times {10}^{6}m/s$
• C. $1.25\times {10}^{7}m/s$
• D. $5\times {10}^{4}m/s$

Answer 1

The correct option is C $1.25\times {10}^{7}m/s$

Ans : (d)

$\omega =50,000;\beta =0.004$

$v_p=\frac{\omega }{\beta }=\frac{5\times {10}^4}{4\times {10}^{-3}}=1.25\times {10}^{7}m/s$