Simple A. C. Circuits - Jamb Physics Past Questions and Answers

Question 1:

• JAMB 1978

Two lamps are rated 40W and 220V each are connected in series. The total power dissipated in both lamps is

A. 10W
B. 20W
C. 40W
D. 80W
E. None of the above

Question 2:

• JAMB 1992

In alternating current theory, the units of impedance, r.m.s. voltage and resonance frequency are respectively equal to

A. Volt, ampere and hertz
B. Ohms, volt and hertz
C. Watt, ohms and radian
D. Ohms, hertz and joule

Question 3:

• JAMB 1992

In A.C circuit theory, the root means square (r.m.s) current, I_rms and the peak (maximum)current I_o are related by

A. I_o = \(\frac{I_rms}{\sqrt{2}}\)
B. I_rms = \(\frac{I_o}{\sqrt{2}}\)
C. I_rms = \(\frac{\frac{I}{I_o}}{\sqrt2}\)
D. I_rms = \(\frac{I_rms}{\sqrt{2}}\)

Question 4:

• JAMB 1995

An alternating source is connected in series to a capacitor of capacity reactance \( 10^3 \sqrt{3} \) and a resistor of resistance 10³ Ohms. The Impedance of the circuit is...

A. \( 2000 \sqrt{3} \) Ohms
B. 2000 Ohms
C. \( 1000 \sqrt{3} \) Ohms
D. 1000 Ohms

Question 5:

• JAMB 1997

The power dissipated in an a.c. circuit with an r.m.s, current of 5A, r.m.s voltage of 10V and a phase angle of 60^o is

A. 25W
B. 50W
C. 120W
D. 125W