Question

In an A.C source, peak value of A.C is the maximum value of current in either direction of the cycle. Root mean square (RMS) is also defined as the direct current which produces the same heating effect in a resistor as the actual A.C.
Does an AC measuring instrument measure it?
A: RMS values
B: peak value
C: average value
D: square of current

Answer 1

AC circuit involves alternating current and voltage. Alternating current changes its value after every half cycle. Also, the amplitude is the same in both the half cycles positive and negative. In an AC circuit, the current and voltage values are sinusoidal so they are constantly changing with the time

Complete step by step answer:
If we use a normal ammeter to measure AC current then it will not show any deflection because during one half cycle current will be positive and the ammeter will deflect in one direction and during the other half the current will be negative and the ammeter will deflect on the opposite direction and this happens so fast that for us the hand of the ammeter appears to be stationary.
In order to come over we use hot wire ammeters because they do not incorporate the direction of current and work on the heating effect. Therefore, hot wire ammeters work perfectly; they measure Root mean square values.

So, the correct answer is “Option A”.

Note:
AC voltage alternates in polarity and AC alternates in direction. That is why it is known as alternating current because it changes in the path after every half cycle and the value of AC over the full cycle is zero.
RMS amplitude measurement is the best way to relate AC quantities to DC quantity and such measurements can be made by using oscilloscopes.