Answer:

Explanation:
As we know that the magnetic field near the center of solenoid is given as

now we know that initially the length of the solenoid is L = 18 cm and N number of turns are wounded on it
So the magnetic field at the center of the solenoid is 2 mT
now we pulled the coils apart and the length of solenoid is increased as L = 21 cm
so we have

now plug in all values in it


Answer:
The capacitance is cut in half.
Explanation:
The capacitance of a plate capacitor is directly proportional to the area A of the plates and inversely proportional to the distance between the plates d. So if the distance was doubled we should expect that the capacitance would be cut in half. That can be verified by the following equation that is used to compute the capacitance in such cases:
C = (\epsilon)*(A/d)
Where \epsilon is a constant that represents the characteristics for the insulator between the plates. A is the area of the plates and d is the distance between them. When we double d we have a new capacitance, given by:
C_new = (\epsilon)*(A/2d)
C_new = (1/2)*[(\epsilon)*(A/d)]
Since C = (\epsilon)*(A/d)] we have:
C_new = (1/2)*C
Answer:
It has <u>greater accuracy than other nondestructive methods in determining the depth of internal flaws and the thickness of parts with parallel surfaces.</u>
Explanation:
Hope this helps you!

When two bodies collide with each other in the absence of an external force, then the total final momentum of the bodies is equal to their total initial momentum.