2006 - WAEC Physics Past Questions and Answers - page 5
41
An electric lamp rated 120W is used on a 240Vrms, calculate the resistance of its filament
A
480\(\Omega\)
B
360\(\Omega\)
C
60\(\Omega\)
D
2\(\Omega\)
42
Which of the following statements about a bar magnet is correct?
A
iron fillings cling uniformly along the length of a bar magnet
B
the magnetic properties are more pronounced at the middle of a magnet
C
it is impossible to have the same poles at the end of a magnet
D
the magnetic properties are more pronounced at points near the end of the bar
correct option: d
Users' Answers & Comments43
The force experienced by a current-carrying conductor move in a magnetic field is employed in the working of the i. moving coil ammeter ii. electric bell iii. electric motor. Which of the statements above are correct?
A
i and ii only
B
ii and iii only
C
i and iii only
D
i, ii and iii
correct option: c
Users' Answers & Comments44
The breaking up of an atomic nucleus into the fragment of nearly equal size is known as
A
nuclear fusion
B
nuclear fission
C
thermonuclear reaction
D
natural radioactivity
correct option: b
Users' Answers & Comments45
A 500kV is applied across an X-ray tube. Calculate the maximum velocity of the electrons produced [Me = 9.1 x 10-31kg, e = 1.6 x 10-19C]
A
4.2 x 108ms-1
B
1.9 x 108ms-1
C
4.2 x 105ms-1
D
1.8 x 105ms-1
correct option: a
Users' Answers & Comments46
A radioactive substance of mass 768g has a half life of 3 years. After how many years does this substance leave only 6g undecayed?
A
21
B
18
C
15
D
12
correct option: a
\(768 \to 384 \to 192 \to 96 \to 48 \to 24 \to 12 \to 6\)
7 x 3 = 21yrs
Users' Answers & Comments7 x 3 = 21yrs
47
Fusion is not usually used for generating electric power because
A
no energy is released when fusion takes place
B
very high temperatures are required to initiate fusion reaction
C
the raw materials needed is not easily available
D
heavy nuclei are involved
correct option: b
Users' Answers & Comments48
An atom \(^{234}_{91} P\) emits a gamma radiation. The resultant nuclide is
A
\(^{230}_{90} Th\)
B
\(^{234}_{91} Pa\)
C
\(^{234}_{90} Th\)
D
\(^{234}_{89} Ac\)
correct option: b
Users' Answers & Comments49
The diagram above shows the speed-time graph of a car.If the car covered a total distance of 600m in 25s, calculate its maximum speed
A
30ms-1
B
25ms-1
C
20ms-1
D
15ms-1
correct option: a
S = \(\frac{1}{2} (a + b)h\)
60 = \(\frac{1}{2}(15 + 25)h\)
h = \(\frac{1200}{40} = 30\)m/s
Users' Answers & Comments60 = \(\frac{1}{2}(15 + 25)h\)
h = \(\frac{1200}{40} = 30\)m/s
50
Determine the magnitude of P in the diagram above
A
16N
B
20N
C
32N
D
40N
correct option: c
X = 50 sin30 = 30 x 0.5 = 25cm
40 x 20 = p x 25
p = \(\frac{40 \times 20}{25}\)
= 32N
Users' Answers & Comments40 x 20 = p x 25
p = \(\frac{40 \times 20}{25}\)
= 32N