Physics Past Questions and Answers

Energy losses through eddy currents are reduced by using

A Low resistance wires
B Insulated soft iron wires
C Few turns of wires
D High resistance wires

Question 37:

A capacitor of 20 x 10^-12F and an inductor are joined in series. The value of the inductance that will give the circuit a resonance frequency of 200kHz is

A I/16 H
B I/8 H
C I/64 H
D I/32 H

Question 38:

The magnetic force on a charged particle moving with velocity v is

A Proportional to both the magnitude of the charge and the velocity v
B Independent of the magnitude of the charge
C Proportional to the velocity v only
D Proportional to the magnitude of the charge only

Question 39:

In the diagram above, which of the simple pendula will resonate with P when set into oscillation

A T
B U
C R and T
D Q and R

Question 40:

The diagram above is a block and tackle pulley system in which an effort of 80N is use to lift a load of 240N. The efficiency of the machine is

A 60%
B 50%
C 40%
D 33%