Question

An arc lamp operates at 80V,10A. Suggest a method to use it with a 240V d.c. source. Calculate the value of the electric component required for this purpose

Answer 1

Given :

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

Answer 2

V 1= 80V
I 1= 10A
R1= V 1 / I 1. ( by ohm's law)
R1= 80/ 10= 8 ohms

V 2 = 240 V
R2= V2/ I 2
R2= 240/10
R2= 24 ohms

resistance required= R2- R1 = 24- 8= 16ohms

the value of the electric component required for this purpose is 16 ohms