When a certain a.c supply is connected to a lamp, it lights with the same brightness as it does with a 12 V d.c battery. Then r.m.s value of the a.c supply is?
-
A.
12.0 V -
B.
3.5 V -
C.
17.0 V -
D.
8.5
Correct Answer: Option A
Explanation
The r.m.s value of an a.c voltage/current is the value of the d.c. voltage/ current that will dissipate the same amount of energy in a given resistance as the a.c. Thus the r.m.s value of the a.c supply is 12v.