Question

What value of direct current must flow through a resistor to produce the same heating power as an alternating current with a peak value of 3.5 A?

(a) 1.5 A

(b) 2.5 A

(c) 3.5 A

(d) 4.5 A

This question was addressed to me in semester exam.

Enquiry is from Kirchhoff’s Laws and Network Solution topic in division Network Theorems Applied to AC Networks of Basic Electrical Engineering

Answer 1

Correct choice is (b) 2.5 A

To explain: Power in dc circuit = Power in ac circuit     (given)

IDC^2R = IRMS^2R

IDC=IRMS

IRMS=I0/√2 = 3.5/√2 = 2.5 A.

IDC=2.5 A.