Question

How much current will an electric bulb draw from a 420 V source. If the resistance bulb filament is 1200 ohm.

Answer 1

given ,

resistance = 1200 ohm (r)

voltage source = 420 V (v)

we know that,

v=Ir

I=v/r

=420/1200

=210/600

=105/300

=21/60

=0.35 ampere

Answer 2

I= V/R

I = 420 /1200= 21/60=7/20=0.35 AMPHERES