Question

The magnetic field in a plane electromagnetic wave is given B_y = 2 × 10^–7 sin (0.5 × 10³x + 1.5 × 10¹¹t)T. The expression for electric field is

(A) E_x = 60 sin(0.5 × 10³x + 1.5 × 10¹¹t)Vm^–1

(B) E_z = 60 sin(0.5 × 10³x + 1.5 × 10¹¹t)Vm^–1

(C) E_z = 60 sin(1.5 × 10¹¹x + 0.5 × 10³t)Vm^–1

(D) E_z = 60 × 10¹⁵ sin(1.5 × 10¹¹x + 0.5 × 10³t)Vm^–1

Answer 1

The correct option is (B) E_z = 60 sin(0.5 × 10³x + 1.5 × 10¹¹t)Vm^–1

Explanation:

B_y = 2 × 10^–7 sin (0.5 × 10³x + 1.5 × 10¹¹t)

Electric field component is perpendicular to direction of propagation and direction of magnetic field will be along z axis.

∴ (E_o / B_o) = C  hence E_o = C × B_o

∴ E_o = 3 × 10⁸ × 2 × 10^–7 = 60 V/m

∴ E_z = 60 sin(0.5 × 10³x + 1.5 × 10¹¹t)V/m