Two circular plates of radius 9cm are separated in air by 2.0mm, forming a parallel

(a)

(b) 5 A

Solution:

As per the question:

Radius of the circular plate, R = 9 cm = 0.09 m

Distance, d = 2.0 mm =

At , current, I = 5 A

Now,

Area, A =

We know that the capacitance of the parallel plate capacitor, C =

Also,

Also,

Now,

(a) The rate of change of electric field:

where

(b) To calculate the displacement current:

where

= Rate of change of flux

Answer;

moving a magnet into a coil of wire in a closed circuit

Explanation;An electromagnet is a type of magnet that runs on electricity. It is created by introducing a magnetic material such as iron in a coil of wire  in a closed circuit. The strength of the electromagnet can be easily changed by changing the amount of electric current flowing in the closed circuit. This is different from the case of a permanent magnet whose strength is constant. Poles of an electromagnet may be reversed by changing the direction of electric current.