The magnitude of the magnetic field at point P for a certain electromagnetic wave is 2.12 μT. What is the magnitude of the electric field for that wave at P? (c = 3.0 × 108 m/s)

The electric field is  

Explanation:

From the question we are told that

     The magnitude of magnetic field is

      The value for speed of light is  

Generally the magnitude of the electric field at point P is

substituting values

Option (B)

Explanation:

mass of car, m = 2000 kg, initial velocity of car, u = 40 m/s,

Force, F = 40,000 N, Final velocity, v = 0 m/s

Let the impact time be t.

By use of Newton's second law

F = m a

where, a be the acceleration and m be the mass.

40000 = 2000 x a

a = 20 m/s^2

Acceleration is negative because the car is stopped.

Use first equation of motion,

v = u + a x t

0 = 40 - 20 x t

t = 2 second