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

=> 
The answer is D. Krypton (kr)
Speed of the car given initially
v = 18 m/s
deceleration of the car after applying brakes will be
a = 3.35 m/s^2
Reaction time of the driver = 0.200 s
Now when he see the red light distance covered by the till he start pressing the brakes


Now after applying brakes the distance covered by the car before it stops is given by kinematics equation

here
vi = 18 m/s
vf = 0
a = - 3.35
so now we will have


So total distance after which car will stop is


So car will not stop before the intersection as it is at distance 20 m