Answer:When the length of a string is changed, it will vibrate with a different frequency.Shorter strings have higher frequency and therefore higher pitch.
Answer:

Explanation:
As we know that the length of the conductor is given as

now if it is converted into a square then we have


now the are of the loop will be

now the magnetic flux is defined as

here we know
B = 1.0 T



Answer:
option (b)
Explanation:
for a telescope, the object is placed very far from the objective lens so the focal length of objective is large and the eye piece is of short focal length.
So, long focal length objective and short focal length eyepiece.
Option (b) is correct.
Answer:
Electrical energy
Explanation:
Electrical energy deals with magnetism and moving electrons