2008 - WAEC Physics Past Questions and Answers - page 5
41
A direct current of 5A flow through a 0.2H inductor. Calculate the energy stored in the inductor
A
0.5J
B
1.0J
C
2.5J
D
5.0J
42
Both \(\gamma\)-rays and X-rays i. can be produced by thermionic emission ii. have low frequencies iii. have short wavelengths. Which of the statements above is/are correct?
A
i only
B
ii only
C
iii only
D
i and iii only
correct option: c
Users' Answers & Comments43
When a radioactive substance undergoes a beta decay, its
A
mass number decreases by 1
B
atomic number decreases by 1
C
mass number increases by 1
D
atomic number increases by 1
correct option: d
Users' Answers & Comments44
Nuclear fission is preffered to nuclear fusion in the generation of energy because
A
very high temperature are required for fusion
B
the raw materials for fusion are easily obtained
C
energy obtained from fusion is relatively small
D
the by-products of fusion is very dangerous
correct option: c
Users' Answers & Comments45
Control in nuclear reactors is effected with boron rods because rhe rods have the ability to
A
absorb electrons
B
absorb neutron
C
accelerate electrons
D
slow down neutrons
correct option: b
Users' Answers & Comments46
A radioactive element has a decay constant of 0.077s-1. Calculate its half-life
A
13.0s
B
9.0s
C
5.1s
D
0.5s
correct option: b
\(t_{\frac{1}{2}} = \frac{0.693}{\lambda} = \frac{0.693}{0.077} = 9s\)
Users' Answers & Comments47
The diagram above shoes three forces F1, F2 and F3, which of the following ewuations is correct?
A
F3 = F1 + F2
B
F2 = F1 + F3
C
F1 = F2 - F3
D
F1 = F2 + F3
correct option: d
Users' Answers & Comments