Physics HELP!!?

Question

a 60 watt filament lamp is operated from an alternating current supply. The RMs voltage of the supply is 240v at a frequency of 50 hz

(i) calculate the maximum current in the filament?

(ii) and show that the maximum power dissipated in the lamp is 120 w

Thanks!

Answer 1

Assuming that the supply is sinusoidal (i.e. a sine wave) then then the RMS voltage is the peak voltage divided by the square root of 2, and the RMS current is the peak current divided by the square root of 2.

A 60 watt lamp has a 60 watt RMS power.

Power = voltage x current

So, knowing the power (60 watt) and the RMS voltage (240VAC) you can compute the RMS current

Knowing the RMS current you can compute the peak current. This gives you part i

Knowing the RMS voltage you can compute the peak voltage.

The peak power is just the product of the peak voltage and the peak current. This gives you part ii