Question

The magnetic field inside a

5.0-cm-diameter solenoid is 2.0 T and decreasing at 3.90 T/s.

What is the electric field strength inside the solenoid at a point on the axis?
What is the electric field strength inside the solenoid at a point 2.40 cm from the axis?

Answer 1

Diameter of the solenoid D = 5.0 cm = 0.05 m

Radius of the solenoid R = D/2 = 0.05/2 = 0.025 m

Now the Magnetic field inside the solenoid be B = 2 T

Rate of decrease of magnetic field be dB/dt = 3.90 T/s

Now electric field E at a distance r from the axis is given by

                         E = r/2 * ( dB/dt)

a)Electric field at a point on the axis

                      here r = 0

                      so     E = r/2 * dB/dt = 0

b) Electric field at a distance from the axis

                             r = 2.40 cm = 0.024 m

                      E = 0.024 * 3.90/2 = 0.0468 V/m