Physics Past Questions and Answers

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 1502:

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 1503:

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 1504:

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 1505:

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