2010 - WAEC Physics Past Questions and Answers - page 5
41
Which of the following factors will increase the sensitivity of moving coil meter?
A
strong spring
B
low numbers of turns
C
small area of coil
D
soft iron core
correct option: d
Users' Answers & Comments42
In order to prevent bar magnets from losing their strength, they are stored wih keepers such that the two bars are placed with
A
like poles facing each other and the keepers placed between them
B
like poles facing each other and the keepers placed between them
C
unlike poles facing each other and the keepers placed at their ends
D
unlike poles facing each other and the keepers placed between them
correct option: c
Users' Answers & Comments43
The energy, E stored in an inductor of inductance L when current I passes through it is given by the equation
A
E = \(\frac{1}{2} LI^2\)
B
E = LI2
C
E \(\frac{1}{2}LI\)
D
E = \(\frac{1}{2} L^2I\)
correct option: b
Users' Answers & Comments44
The resonant frequency of an a.c circuit is 1000 kHz. If each of the capacitance and inductance in the circuit is reduced by 50%, and no other changes are made, the resonant frequency will become
A
250kHz
B
750kHz
C
1000kHz
D
2000kHz
correct option: d
Users' Answers & Comments45
Eddy currents can be reduced by
A
using coil of high resistance
B
winding the coil on a soft iron core
C
creating holes in the metal plates
D
using coil of low resistance
correct option: c
Users' Answers & Comments46
an electron moves with a speed of 2.0 x 106ms-1 in a straight line. Calculate the wave length of the electron wave. [mass of an electron = 9.1 x 10-31 kg][Planck's constant = 6.6 x 10-34Js]
A
3.63 x 10-19m
B
6.51 x 10-9m
C
4.24 x 10-8m
D
7.25 x 10-8m
correct option: c
\(\lambda = \frac{hc}{\frac{1}{2}mv^2} = \frac{6.6 \times 10^{-38} \times 3 \times 10^8}{\frac{1}{2} \times 9.1 \times 10^{-31} (2 \times 10^6)^2}\)
= 4.24 x 10-8m
Users' Answers & Comments= 4.24 x 10-8m
47
Oxidation of the filament in a light bulb is prevented by the introduction of
A
hydrogen
B
oxygen
C
argon
D
mercury vapour
correct option: c
Users' Answers & Comments48
In a cathode ray tube, the function of the x-plates is to
A
deflect the electron beam horizontally
B
deflect the electron beam vertically
C
reflect the electron beam
D
generate sinusoid waves
correct option: a
Users' Answers & Comments49
A nuclide represented as \(^{70}_{32}X\) has a neutron-proton ratio of
A
0.5
B
0.8
C
1.2
D
1.5
50
Neutrons are used to induce artificial radioactivity because they
A
are energetic
B
have no charge
C
have no mass
D
are ionizing
correct option: b
Users' Answers & Comments