Question

Calculate the number of electrons drifting per second through the filament of a 100 W- 220 V bulb , when glowing.(e = 1.6 * 10^ -19 )?

Answer 1

For a 100 W-220 V bulb to be sustained we must find the current required using the following formula:

`P=VI`

`100=220 times I`
`I=0.4545...` Ampere

Current=(Charge/time)

`I=(Deltaq)/(Deltat)`

(t=seconds)

Plugging in our values:
t=1 second
Hence:
`q=0.4545 C`

1 electron has a charge of `1.6 times 10^-19 C` and we need 0.4545 Coloumb/second to make the lamp glow.

"How many times does `1.6 times 10^-19` fit in 0.4545?"
We use division!

`(0.4545)/(1.6 times 10^-19)=2.84 times 10^18`

So every second, `2.84 times 10^18` electrons drift through the filament.