Post Utme Physics Past Questions and Answers

Question 296:

A bar magnet is most effectively demagnetized by ____________

A. Placing it in a N 5 position and hitting it with a hammer
B. Subjecting it to an electric current from a battery
C. Bringing its north pole in contact with the north pole of a very strong magnet
D. Heating the magnet

Question 297:

Which of the following is not true about semi-conductor?

A. Moving holes are equivalent to moving positive charges
B. There are two kind of charges carrier; free electron and hole
C. The escape of a vale nee electron from an atom produces electron holes pair of charge carrier
D. Increase in temperature increases its electrical resistance

Question 298:

The minimum energy necessary to remove an electron from a given atom at infinity is called ____________

A. Excitation
B. Ground state energy
C. Ionizing energy
D. Binding energy

Question 299:

Find the de Broglie wavelength of a 0.01kg pallet having a velocity of 10m/s and energy: 6.63 x10³⁴ is ____________

A. 6 .63 x\( 10^31\)m
B. 6.63 x\(10^{-32}\) m
C. 6 .63 x \(10^{-33}\) m

Question 300:

A set-up transformer is designed to operate from a 25v supply. If the transformer is 80% efficient, determine the current in the primary coil when the output terminals are not connected to 240v 100w lamp

A. 5.0A
B. 4 0A
C. 2.5A
D. 2.0A