AP EAMCET20227 Jul 2022Morning ShiftPhysicsElectromagnetic WavesActual
The equation that represents magnetic field of a plane electromagnetic wave which is propagating along x -direction with wavelength 10 ~mm and maximum electric field 60 Vm ⁻¹ in y -direction is (where, c= speed of light)
Options
- A(6 10⁻⁷ ) [0.2 (c t-x)] k T
- B(2 10⁻⁷ ) [200 (c t-x)] k T
- C(2 10⁻⁷ ) [200 (c t-x)] i ~T
- D(6 10⁻⁷ ) [02 (c t-x)] i T
Correct answer
B. (2 10⁻⁷ ) [200 (c t-x)] k T
Step-by-step solution
Equation of magnetic field of an electromagnetic wave is given by B=B₀ ( t-k x) k =B₀ (2 f t- 2 x ) k [ =2 f . and .k= 2 ]=B₀ 2 [f t-x] k B=B₀ 2 [c t-x] k ...(i) Also direction of B vector is perpendicular to E and also to direction of propagation And B₀= E₀ c Here, E₀=60 Vm ⁻¹ B₀= 60^ 3 10^8 =2 10⁻⁷ Also k= 2 Here k=200 = 2 = 1 100 ~m = 100 100 ~cm =10 ~mm =10⁻² ~m Putting the values is eq. (i), we get B=2 10⁻⁷ [ 2 10⁻² (c t-x) ] k =2 10⁻⁷ 200 (t-x) k