Post Utme Physics Past Questions and Answers

Question 126:

Dispersion of light by a glass prism is due to the ____________

A. Different hidden colours of the glass
B. Different speeds of their various colours in glass
C. Defects in the glass
D. High density of glass

Question 127:

A guitar string of length \(33 \mathrm{~cm}\) is under a tension of \(55 \mathrm{~N}\). If the fundamental frequency is \(196 \mathrm{~Hz}\), find the speed of wave on string.

A. \(6 \mathrm{~m} / \mathrm{s}\)
B. \(0.33 \mathrm{~m} / \mathrm{s}\)
C. \(129 \mathrm{~m} / \mathrm{s}\)
D. None

Question 128:

A transformer has 400 turns as its primary winding and 100 turns as secondary winding.
If the primary coil is connected to a \(12 \mathrm{~V}\) source, the transformer functions as ____________

A. A step-down transformer with secondary emf \(=6 \mathrm{~V}\)
B. A step-down transformer with secondary emf \(=3 \mathrm{~V}\)
C. A step-up transformer with secondary emf- 24V
D. A step-up transformer with secondary emf- \(48 \mathrm{~V}\)

Question 129:

A battery of internal resistance of \(2 \Omega\) has a voltage of 4.0V when supplying a current of 2.0A
Calculate the terminal voltage if it now supplies a current of \(3.0 \mathrm{~A}\)

A. \(2.0 \mathrm{~V}\)
B. \(6.0 \mathrm{~V}\)
C. \(1.5 \mathrm{~V}\)
D. \(12.0 \mathrm{~V}\)

Question 130:

The purpose of a dielectric material in a parallel plate capacitor is to ____________

A. Increase its capacitance
B. Decrease its capacitance
C. Insulate the plates from each other
D. Increase the magnetic field between them