Answer:
BA
0

Explanation:
B = Magnetic field
A = Area
= Angle
t = Time taken
Before rotation the magnetic flux is given by

Magnetic flux is BA
After rotation the magnetic flux is given by

The magnetic flux is 0
Magnitude of emf is given by

The magnitude of the average emf induced in the entire coil is 
C the correct but not sure?
Answer: 4.8 s
Explanation:
We have the following data:
the mass of the raft
the force applied by Sawyer
the raft's final speed
the raft's initial speed (assuming it starts from rest)
We have to find the time 
Well, according to Newton's second law of motion we have:
(1)
Where
is the acceleration, which can be expressed as:
(2)
Substituting (2) in (1):
(3)
Where 
Isolating
from (3):
(4)
Finally:
Answer:
I = 2172.46 A
Explanation:
Given that,
The length of a solenoid, l = 2.1 m
The inner radius of the solenoid, r = 28 cm = 0.28 m
The number of turns in the wire, N = 1000
The magnetic field in the solenoid, B = 1.3 T
We need to find the current carried by it. We know that, the magnetic field in a solenoid is given by :

Put all the values,

So, it carry current of 2172.46 A.