JEE Main202227 Jul 2022Morning ShiftPhysicsElectromagnetic WavesActual
A beam of light travelling along X -axis is described by the electric field E y = 900 sin ω t - x c . The ratio of electric force to magnetic force on a charge q moving along Y -axis with a speed of 3 × 10 7 m s - 1 will be : [Given speed of light = 3 × 10 8 m s - 1 ]
Options
- A1 : 1
- B1 : 10
- C10 : 1
- D1 : 2
Correct answer
C. 10 : 1
Step-by-step solution
Given, E y = 900 sin ω t - ω x c Here, E 0 = 900 Electric field and electric force are related as F E = q E 0 Magnetic force of a moving charge is given by F B = q v B 0 Thus, the ratio F E F B = E 0 v B 0 Using relation between magnetic and electric field, we have F E F B = c v = 3 × 10 8 3 × 10 7 = 10 : 1