Physics Past Questions and Answers

The resistivity, \(\mathit{P}\), of a material of length l, cross-sectional area A, resistance R, is given by the equation

A \(\mathit{P} = \frac{RA}{l}\)
B \(\mathit{P} = \frac{l}{RA}\)
C \(\mathit{P} = \frac{Rl}{A}\)
D \(\mathit{P} = \frac{R}{Al}\)

Question 3632:

A wire of length 30cm is moved with a speed of 2ms<sup style='font-size: smaller;'>-1</sup> at right angles to a magnetic field of flux density 0.4T. calculate the emf induced in the wire

A 0.15V
B 0.24V
C 2.70V
D 24.00V

Question 3633:

Which of the following practices will lead to losses in electrical power transmission?

A Using transmission cables of large diameter
B Transmitting at high voltage and low current
C Transmitting at relatively low voltage and high current
D Using a set-up transformer at the production end

Question 3634:

For photoelectric emission, the threshold frequency is the

A Maximum frequency of incident radiation that will eject elecrons
B Minimum fraquency of incident radiation required to eject elecrons
C Frequency which results in the emission of the greater number of electrons
D Fraquency whch impacts greatest kinetic energy to emitte electrons

Question 3635:

Which of the following properties is not applicable to X-rays? They

A Travel in straight lines
B Travel with the speed of light
C Are deflected by magnetic field
D Affect photographic films