Answer:
The value is 
Explanation:
From the question we are told that
The diameter of the ring is 
The length of the solenoid is 
The diameter of the solenoid is 
The number of turns is N = 1500
The change in current in the solenoid is 
The time taken is 
Generally the radius of the ring is

=> 
=> 
Generally the area of the ring is mathematically represented as

=>
=> 
Generally the induced emf is mathematically represented as

Here

Here
is the permeability of free space with value

So

=> 
So

=> 
Red clothes look red because they REFLECT the red light, and absorb light of other colors.
W = 1/2k*x^2.
k = spring constant = 2500 n/m.
x = distance = 4 cm = 0.04m (convert to same units).
W = 1/2(2500)(0.04)^2 = 2J.
Hydrogen fuel cells is the answer