Question

. An arc lamp operated at 80 V takes 10 A current. How
much resistance should be connected in series with
the lamp to use it at 240 V mains so that it takes the
same current?
Ans. 16​

Answer 1

Answer:

An arc lamp is operated at :

Voltage V1=80V

current=I1=10 A

By Ohm's law, V=IR

R=V/I=80/10=8 Ohms.

Now voltage is increased to 240V=V2

Resistance required to supply 10A current would be=R2=240/10=24ohms

Resistance required:

=R2-R1=24-8=16ohms

∴The value of the electric component required  is 24ohms