Question

1. One billion electrons pass from a point P towards
another point Q in 10s. What is the current in
ampere? What is its direction?​

Answer 1

Here, number of electron, n=10000000=10

7

Total charge on ten million electrons is

Q=ne[Where e=1.6×10

−19

C]

=10

7

×1.6×10

−19

C=1.6×10

−12

C

Time taken by ten million electrons to pass from point P to point Q is t=I μs=10

−6

s

The current

I=

t

Q

=

10

−6

1.6×10

−12

=1.6×10

−6

A

Since the direction of the current is always opposite to the direction of flow of electrons. Therefore due to flow of electrons from point P to point Q the current will flow from point Q to point P.

Answer 2

The direction of current is opposite to the direction of electron. Hence, it is from Q to P.