Hello
You expect to see:
1) A solar eclipse, when the earth is between the sun and the moon: the shadow of the earth is projected on the moon surface, and the sun will appear dark
2) An "earth eclipse", when the moon is between the sun and the earth: the shadow of the moon is projected on the earth surface, therefore the earth will appear dark.
Answer:
Friction force is 0.1375 N
Solution:
As per the question:
Radius of the metal disc, R = 4.0 cm = 0.04 m
Magnetic field, B = 1.25 T
Current, I = 5.5 A
Force on a current carrying conductor in a magnetic field is given by considering it on a differential element:
Integrating the above eqn:
(1)
Now the torque is given by:
(2)
From eqn (1) and (2):
Thus the Frictional force is given by:
It's momentum is twice as much.