Answer:

Explanation:
If we assume that the Earth is a spherical conductor, according to Gauss's Law, the electric field is given by:

Here k is the Coulomb constant, the excess charge on the Earth's surface and r its radius. Solving for q:

Answer:
Part a)

Part b)
Since the radius is decreasing so induced current will increase the flux through the coil
So it would be clockwise in direction
Explanation:
As we know that magnetic flux linked with the coil is given as

now the rate of change in flux is given as

now we know that circumference is decreasing at rate of 15 cm/s
so here we know the length of circumference as

So rate of change in circumference is


final length of circumference at t = 8 s

Part a)
Now the induced EMF is given as



Part b)
Since the radius is decreasing so induced current will increase the flux through the coil
So it would be clockwise in direction
Answer:
R = 60 Ω
Explanation:
given,
Potential of the certain device, V = 120 V
current rating of the circuit, I = 20 A
resistance of the device, R = ?
Using Ohm's Law
V = I R
R = 60 Ω
hence, the resistance of the device is equal to 60 Ω