Q.

A current is made of two components, a DC component of I1=3 amp and an AC component given by I2=42sinωt amp; then the reading of the hot-wire ammeter (rms value) is:

1 3  amp  
2 42  amp  
3 (3+42)  amp  
4 5  amp  

Ans.

(4)

I1=3A,  I2=42sinωt

Inet=I1+I2=(3+42sinωt)

Irms=32+(42)2×12=5A