Waec Physics 2012 Past Questions and Answers

Question 41:

• WAEC 2012

Which of the following modes is the most economical method of transmitting electrical power over long distances?

A. Alternating current at low voltage and high current
B. Alternating current at high voltage and high current
C. Alternating current at high voltage and low current
D. Direct current at low voltage and high current

Question 42:

• WAEC 2012

An inductor is connected to a 24V, 50Hz mains supply. If the current through the inductor is 1.5A, calculate the inductance of the inductor (\(\pi = \frac{22}{7}\))

A. 8.0 x 10²H
B. 7.5 x 10^oH
C. 1.6 x 10^oH
D. 5.1 x 10^-2H

Question 43:

• WAEC 2012

In a R-C circuit

A. I^rms leads V^rms by 60^o
B. I^rms slags V^rms by 60^o
C. V^rms lags I^rms by 90^o
D. V^rms leads I^rms by 90^o

Question 44:

• WAEC 2012

An atom in an excited state is one whose

A. Potential energy is minimum
B. Potential energy is maximum
C. Electron are in the conduction band
D. Electron have moved to higher energy level

Question 45:

• WAEC 2012

A metal with a work function of 3.0ev is irradiated with ultraviolet light of energy 4.0 ev. The kinetic energy of the ejected electron is

A. 1.0eV
B. 3.0eV
C. 4.0eV
D. 7.0eV