Which statement below is correct?
a.
the moon revolves around the sun, but the earth does not.
b.
the earth-moon system revolves around the sun.
c.
the earth revolves around the sun-moon system.
d.
the sun revolves around the earth-moon system.

The correct answer is:

(B) The Earth-Moon system revolves around the Sun.

Because the Earth revolves around the sun while the Moon revolves around the Earth.

Part a)

Rate of charge flow is known as electric current

Part b)

Average current flow is

Part c)

As we know that current density is current per unit area

Explanation:

As we know that angular frequency of rotation is

now by basic definition of electric current

Part a)

Rate of charge flow is known as electric current

so here we have

Part b)

here we know that

now we have

Part c)

As we know that current density is current per unit area

So we have