160W-60V lamp is connected at 60 V DC supply. The number of electrons passing through the lamp in 1 min is
(The charge of electron, `e=1.6xx10^(-19)C`)

Options

A. `10^(19)`
B. `10^(21)`
C. `1.6xx10^(19)`
D. `1.4xx10^(20)`

Answer

B

Explanation

Power, `P = (V^(2))/(R )`
and `R =(V^(2))/(P)=((60)^(2))/(160)=22.5 Omega`
Now, according to Ohm's law
V = lR
`therefore " " l=(60)/(22.5)`
`rArr " " l = 2.6 A`
Here, t = 60 s
As `l=("ne")/(t)`
`rArr " " n=(l xx t)/(e)=(2.6xx60)/(1.6xx10^(-19))~~ 10^(21)`