Question

An electromagnetic wave travels along the z-axis. At a certain point in space, the electric field is \( 8.7 \, \text{Vm}^{-1} \) along the x-axis. What is the magnitude of the magnetic field along the y-axis?

• A. \( 2.9 \times 10^{-8} \, \text{T} \)
• B. \( 3 \times 10^{-6} \, \text{T} \)
• C. \( 8.7 \times 10^{-6} \, \text{T} \)
• D. \( 3 \times 10^{-5} \, \text{T} \)

Hint:

Use \( B = \frac{E}{c} \) in EM wave propagation, where \( c = 3 \times 10^8 \, \text{ms}^{-1} \).

Answer 1

The Correct Option is A

In electromagnetic waves: \[ E = cB \Rightarrow B = \frac{E}{c} = \frac{8.7}{3 \times 10^8} = 2.9 \times 10^{-8} \, \text{T} \]