Question

The current in an ideal, long solenoid is varied at a uniform rate of 0.01A/s. The solenoid has 2000turns/m and its radius is 6.0cm. (a) Consider a circle of radius 1.0cm inside the solenoid with its axis coinciding with the axis of the solenoid. Write the change in the magnetic flux through this circle in 2.0seconds, (b) Find the electric field induced at a point on the circumference of the circle, (c) Find the electric field induced at a point outside the solenoid at a distance 8.0cm from its axis.

Answer 1

di/dt = 0.01A/S

For 2s(di/dt) = 0.02A/S

n = 2000turn/m, R = 6.0cm = 0.06m

r = 1cm = 0.01m

(a) ϕ = BA

= 4π × 10^–7 × 2 × 10³ × π × 1 × 10^–4 × 2 × 10^–2 [A = π × 1 × 10^–4]

= 5.64 × 10^–7V/m