Post Utme Physics Past Questions and Answers

Question 156:

To produce an enlarged and erect image with a concave mirror, the object must be positioned ____________

A. Between the principal focus and the centre of curvature
B. At the principal focus
C. Between the principal focus and the pole
D. Beyond the centre of curvature

Question 157:

To convert an ac dynamo to dc dynamo, the ____________

A. Number of turns of the coil is increased
B. Slip rings are replaced with a split-ring commutator
C. Number of turns of the" coil is reduced
D. Split-ring commutator is replaced with slip rings

Question 158:

In an AC circuit that contains only a capacitor, the voltage ____________

A. Lags behind the current by 90°
B. Leads the current by 90°
C. Lags behinds the currents by 180°
D. Leads the current by 180°

Question 159:

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

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

Question 160:

A substance has a half-life of 3min. After 6m the count rate was observed to be 600. What its count rate at zero time?

A. 200
B. 1200
C. 1600
D. 2400