What is the electric potential at a point distance r from a proton of charge q placed in a medium of permittivity εo?
Aq2/4πεor2
Bq/4πεor2
Cq2/4πεor
Dq/4πεor
E4πεoq2r
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Question 1882
waec1992
The diagrams above show lines of force in electric fields. In which of the diagrams would a positive test charge experience the least force as it moves from x to y?
AI only
BII only
CIII only
DI and II only
EII and III only
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Question 1883
waec1992
Calculate the energy stored in 20μF capacitor if the potential difference between the plates is 40 V.
A3.2 x10-2J
B1.6x102J
C8.0x10-4J
D4.0x10-4J
E2.0x10-4J
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Question 1884
waec1992
Which of the following statements is not correct?
AA magnetic Held is a region where a magnetic force can be detected.
BMagnetic fields are scalar quantities.
CThe magnitude of the magnetic force experienced by a moving charge depends on the speed on the charge.
Dthe angle between the direction of the earth’s magnetic held and the horizontal is called the angle of dip.
EIron filings can be used to trace out the magnetic field around a bar magnet.
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Question 1885
waec1992
Lenz’s law of electromagnetic induction states that
Aelectromotive force is induced in a circuit whenever there is a change in the magnetic flux linked with the circuit
Bthe induced current in a conductor is in such a direction as to oppose the change producing it
Cthe induced e.m.f. in a circuit is proportional to the rate of change of number of lines of force linking the circuit
Da force is exerted on a current carrying conductor in a magnetic field
Ethe induced e.m.f. is proportional to the current producing the magnetic flux.
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Question 1886
waec1992
Calculate the time in which 4.8 kJ of energy would be expended when an electric heater of resistance 1.8 x 103Ω is used on a 240 V mains supply. (Neglect heat losses to the surrounding).
A150.0s
B90.0s
C36.0s
D20.0s
E2.7s.
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Question 1887
waec1992
In a domestic circuit, electrical appliances and lamps are arranged in parallel across the mains so as to enable the
Asame current to flow through the electrical appliances and the lamps
Bmaximum energy to be consumed at least cost
Csame fuse to be used for the electrical appliances and the lamps
Dvoltage across the appliances not to be affected when the lamps are switched on and off
Eheat losses to be minimized
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Question 1888
waec1992
Calculate the length of a constantan wire of cross- sectional area 4 π x 10-8m2 and resistivity 1.1 x 10-6 Ω m required to construct a standard resistor of resistance 21 Ω. [Take π = 22/7]
A0.42m
B2.40 m
C6.25 m
D183.75 m
E590.00 m
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Question 1889
waec1992
Which of the following is not a consequence of hydrogen bubbles covering the copper plate of a primary cell?
APolarization
BLocal action
CFormation of hydrogen electrode
DIncrease in the resistance of the cell
EGeneration of less current by the cell
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Question 1890
waec1992
Calculate the rate at which energy is used up in the circuit illustrated by the diagram
A0 W
B2 W
C4 W
D8 W
E16 W
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Question 1891
waec1992
A negatively charged rod is brought near the cap of a gold-leaf electroscope. The cap is earthed momentarily while the rod is near to it. The rod is then removed. Which of the following is correct?
AThe cap will be positively charged and the negatively charged leaves will diverge
BThe cap will be negatively charged and the positively charged leaves will diverge
CThe cap and the leaves will be positively charged
DThe cap and the leaves will be negatively charged.
EThe leaves will not diverge because the cap has been earthed.
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Question 1892
waec1992
The diagram above shows the magnetic field around a bar magnet which has its N-pole pointing north. The neutral points in the field are likely to occur at
A1 and 2
B3 and 4
C5 and 6
D7 and 8
E9 and 10
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Question 1893
waec1992
A pipe closed at one end is 1.0m long. The air in the pipe is set into vibration and a fundamental note of frequency 85Hz is produced. Calculate the velocity of sound in the air. (Neglect end correction).
A340.0ms-1
B33Oms-1
C170ms-1
D85.0ms-1
E42.5ms-1
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Question 1894
waec1992
Which of the following statements is not true?
AMusical notes consist of the combination of sounds of regular frequency
BThe combination of overtones produced by an instrument determines the quality of the sound
Cthe loudness of sound is determined by its frequency
Dthe pitch of a note depends on the frequency of vibration of the source
ENoise can be produced by a combination of sounds of irregular frequency
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Question 1895
waec1992
Which of the following waves are longitudinal waves? l. Ripples on the surface of water II. Waves produced by a tuning fork vibrating in air III. Light waves
IV. Waves produced by a flute
AI and II only
BI and III only
CII and III only
DII and IV only
EIII and IV only
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Question 1896
waec1992
How far from a cliff should a boy stand in order to hear the echo of his clap 0.9s later? (Speed of sound in air = 330 ms-1)
A36.67m
B74.25m
C148.50m
D297.00
E366.67m
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Question 1897
waec1992
Which of the following radiations have the highest frequency?
ARadio waves
BLight waves
CX-rays
Dinfra-red rays
EUltraviolet rays
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Question 1898
waec1992
The diagram above shows a waveform in which energy is transferred from A to B in a time of 2.5 x 10-3s. Calculate the frequency of the wave
A2.0 x 103Hz
B1.0 x 103Hz
C4.0 x 10-2Hz
D1.0 x 10-3Hz
E5.0 x 104Hz.
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Question 1899
waec1992
The change of the direction of a wavefront as a result of a change in the velocity of the wave in another medium is called
Arefraction
Breflection
Cdiffraction
Dpolarization
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Question 1900
waec1992
The angle of deviation of light of various colours passing through a glass prism decreases in the order of
