Question

A domestic filament lamp draws a current of 0.72A from a 230V a.c. supply. (A.C. 2.2) Calculate the resistance of the filament. Would you expect the resistance to be the same when you connect the lamp to a 1.5 V battery?

Answer 1

319.44 Ω

Yes

Step-by-step explanation:

The relationship between voltage, current, and resistance is given by

`V=IR`

where

V= voltage

I = current

R = resistance

Now in our case, we are told that V = 230V a.c and I = 0.72 A; therefore, the above equation gives

`230=0.72R`

Dividing both sides of the above equation by 0.72 gives

`R=(230)/(0.72)`
`\boxed{R=319.44\; \Omega}`

Hence, the resistance of the filament is 319.44Ω.

Since the resistance of the filament is independent of the circuit, its value must not change as we connect it with different voltage sources. Therefore, connecting our filament to a 1.5V battery will not change its resistance.