A machine has an efficiency of 80%. If the machine is required to overcome a load of 60N with a force of 40N, calculate its velocity ratio.
A0.53
B0.83
C1.20
D1.50
E1.88
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Question 22
neco2003
Calculate the amount of heat generated in an external load of resistance 8Ω if an alternating current of peak value 5 A is passed through it for 100s.
A2.0 × 104J
B1.0 × 104J
C5.0 × 103J
D4.0 × 103J
E2.0 × 102J
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Question 23
neco2003
Evaporation of a liquid produces cooling of the liquid because the
Aattraction between the vapour molecules and the liquid molecules is great
Baverage kinetic energy of the liquid is reduced
Cdensity of the liquid decreases
Dvapour pressure above the liquid rises
Evolume of the liquid decreases
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Question 24
neco2003
Which of the following instruments can be used to measure e.m.f. most accurately.
AAmmeter
BGalvanometer
CMetre bridge
DPotentiometer
EVoltmeter
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Question 25
neco2003
Young’s modulus of elasticity is the ratio of stress to strain, provided the load does not exceed the
Abreaking point
Belastic limit
Cplastic limit
Dstress limit
Eyield point
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Question 26
waec2003
The bar magnet illustrated in the diagram above picks up an unmagnetised steel nail X. In turn, X picks up a similar nail Y and so on. The nail are said to be magnetised by
Aconduction
Bsingle touch
Cinduction
Ddivided touch
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Question 27
waec2003
The diagram above shows the resultant electric field pattern due to two electric point charges P and S. Which of the following statements is correct?
AP is negatively charged while S is positively charged
BP is positively charged while S is negatively charged
Cboth P and S are positively charge
Dboth P and Q are negatively charged
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Question 28
waec2003
Which of the following reactions represents nuclear fusion?
A\(^2_1H + ^2_1H \to ^3_2He + ^1_0n\)
B\(^235_92U + ^1_0n \to ^145_56Ba + ^90_36Kr \)
C\(^234_90TH \to ^0_-1n + ^3_2He + ^1_0Pa\)
D\(^238_92U \to ^4_2H \to ^3_2He + ^234_90Th\)
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Question 29
waec2003
Nuclear fission is preferred to nuclear fusion in the generation of energy because?
Avery high temperature are required for fusion
Bthe raw material of fusion are not easily obtained
Cenergy obtained from fusion is relatively smaller
Dthe by product of fusion are very dangerous
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Question 30
waec2003
The minimum energy required to remove an electron from an atom is known as
Aexcitation energy
Bionization energy
Cbinding energy
Dphoton energy
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Question 31
waec2003
A radioactive element has a decay constant of 0.077s-1, calculate its half life
A12.5s
B9.0s
C5.1s
D0.5s
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Question 32
waec2003
Which of the following statements is true of ultra violet radiations? It
Asupports the sensation of hearing
Bdoes not cause the emission of electrons from metals
Cis an electromagnetic wave
Dis not capable of causing sun burns
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Question 33
waec2003
Which of the following statements is not true of the isotopes of an element? They
Aare atoms of the same element
Bhave the same chemical properties
Chave the same atomic number
Dhave the same mass number
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Question 34
waec2003
Which of the following statements about an electromagnet is not correct?
Ait is a temporary magnet
Bits strength depends on the current
Cits stength depends on the number of turns in its coil
Dit has permanent poles
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Question 35
waec2003
The direction of induced current in a straight wire placed in magnetic field is determined by using?
AFleming's right hand rule
BMaxwell's screw rule
CFaraday's law
DLenz's law
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Question 36
waec2003
One difference between a reactance and a resistance in an alternating current circuit is
Aresistance is larger than reactance
Benergy is not diaaipated in a reactance
Cenergy is stored in a resistance but not in a reactance
Dthe current in a reactance is lower than in the resistance
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Question 37
waec2003
The maximum power dissipated by a 100\(\Omega\) resistor in a circuit is 4W. Calculate the voltage across the resistor
A10V
B20V
C25V
D400V
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Question 38
waec2003
A lamp is rated 240V 60W, calculate the resistance of its filament
A240\(\Omega\)
B360\(\Omega\)
C960\(\Omega\)
D1440\(\Omega\)
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Question 39
waec2003
A current of 10A passes through a conductor for 10s, calculate the charge flowing through the conductor
A100.0C
B10.0C
C1.0C
D0.1C
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Question 40
waec2003
Which of the following factors does not affect the the electric resistance of a wire?
