Jamb Physics 1992 Past Questions and Answers

Question 36:

• JAMB 1992

The heat produced in a conductor carrying an electric current is

A. Inversely proportional to the current and the resistance
B. Directly proportional to the current, resistance and the time
C. Inversely proportional to of the resistance, current and the time
D. Directly proportional to the square of the current, the resistance and the time

Question 37:

• JAMB 1992

The maximum permissible current through a galvanometer G of internal resistance 10\(\Omega\) is 0.05A. A resistance R is used to convert G into a voltmeter with a maximum reading of 100V. Find the value of R and how it is connected to G

A. 20,000 ohms in parallel
B. 19,990 ohms in series
C. 1990 ohms in series
D. 100 ohms in series

Question 38:

• 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 39:

• 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 40:

• JAMB 1992

The threshold of frequency for photoelectric effect depends on the

A. Intensity of incident light
B. Frquency of incident light
C. Material of the photocathode
D. Potential difference between the cathode and the anode