A ring with an 18mm diameter falls off a scientist's finger into the solenoid in the lab. The solenoid is 25 cm long, 5.0 cm in diameter and has 1500 turns. When turned on, the current in the solenoid is increases linearly to 20 A in 1 second. What is the induced emf in the ring

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

=>  

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me