2011 - WAEC Physics Past Questions and Answers - page 5
41
A wire of length 30cm is moved with a speed of 2ms-1 at right angles to a magnetic field of flux density 0.4T. calculate the emf induced in the wire
A
0.15V
B
0.24V
C
2.70V
D
24.00V
correct option: b
Users' Answers & Comments42
Which of the following practices will lead to losses in electrical power transmission?
A
using transmission cables of large diameter
B
transmitting at high voltage and low current
C
transmitting at relatively low voltage and high current
D
using a set-up transformer at the production end
correct option: c
Users' Answers & Comments43
For photoelectric emission, the threshold frequency is the
A
maximum frequency of incident radiation that will eject elecrons
B
minimum fraquency of incident radiation required to eject elecrons
C
frequency which results in the emission of the greater number of electrons
D
fraquency whch impacts greatest kinetic energy to emitte electrons
correct option: b
Users' Answers & Comments44
Which of the following properties is not applicable to X-rays? They
A
travel in straight lines
B
travel with the speed of light
C
are deflected by magnetic field
D
affect photographic films
correct option: c
Users' Answers & Comments45
Uranium-234 disintegrated to form Thorium-230 by emitting
A
alpha particles
B
gamma rays
C
beta negative rays
D
beta positive rays
correct option: a
Users' Answers & Comments46
The change in mass of fuel during a nuclear reaction is 2.0 x 10-27 kg. Calculate the amount of energy released. (Speed of light = 2.0 x 108ms-1)
A
1.8 x 10-10J
B
9.0 x 10-11J
C
6.0 x 10-19J
D
1.2 x 10-45J
47
Nuclear fusion is not used as a source of enegy because
A
very high temperature is needed for the reaction
B
the fuel for the reaction is not easy to obtain
C
less energy is released
D
the reaction is too slow
correct option: a
Users' Answers & Comments48
Using the circuit diagram above. Calculate the total charge in the circuit
A
80\(\mu C\)
B
35\(\mu C\)
C
20\(\mu C\)
D
16\(\mu C\)
correct option: d
C - \(C_1 + C_2 = 2 + 6 = \mu F\)
\(\frac{1}{C} = \frac{1}{C_1} + \frac{1}{C_1} + \frac{1}{C_2} = \frac{1}{8} + \frac{1}{2}\)
C = \(\frac{8}{5 \mu F}\)
Q = CV
= \(\frac{8}{5} \times 10 = 16\mu C\)
Users' Answers & Comments\(\frac{1}{C} = \frac{1}{C_1} + \frac{1}{C_1} + \frac{1}{C_2} = \frac{1}{8} + \frac{1}{2}\)
C = \(\frac{8}{5 \mu F}\)
Q = CV
= \(\frac{8}{5} \times 10 = 16\mu C\)
49
Using the circuit diagram above. Calculate the potential difference across the capacitors in parallel
A
10.0V
B
8.0V
C
6.7V
D
2.0V