1997 - WAEC Physics Past Questions and Answers - page 5
41
The current in a series R-L-C circuit attains its maximum value when the
A
Impedance is greater than the capacitive reactance
B
Inductive reactance is equal to the capacitive reactance
C
Inductive reactance is greater than the capacitive reactance
D
capacitive reactance is less than resistance
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42
A charge of 1 x \(10^{-5}\)C experiences a force of 40N at a certain point in space. What is the magnitude of the electric field intensity at the point in Newton and couloumb
A
8 x \(10^{6}\)
B
4 x \(10^{6}\)
C
3 x \(10^{-4}\)
D
2 x \(10^{-4}\)
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43
A capacitor of capacitance 25µF is connected to an a.c power source of frequency 200/πHz. Calculate the reactance of the capacitor
A
0.01Ω
B
0.02Ω
C
50Ω
D
100Ω
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44
During the electrolysis of copper (II) tetraoxosulphate (VI) solution, an ammeter shows a steady reading of 1A for 30minutes while 6.6 x \(10^{-4}\)kg of copper is liberated. Calculate the error in the ammeter The electrochemical equivalent of copper is 3.30 x \(10^{-7}kgC{-1}\)
A
0.001A
B
0.011A
C
0.111A
D
1A
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45
In a nuclear reaction, the mass defect is 2 x \(10^{-6}\)g. Calculate the energy released given that the velocity of light is 3 x \(10^{8}ms^{-1}\)
A
9 x \(10^{7}\)J
B
1.8 x \(10^{8}\)J
C
1.8 x \(10^{9}\)J
D
9 x \(10^{-10}\)J
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46
An atom radiates 1.5 x \(10^{-19}\)J of energy when an electron jumps from one energy level to another. What is the wavelength of the emitted radiation? (Planck’s constant =6.6 x \(10^{-34}\)Js. Speed of light in air=3 x \(10^{8}ms^{-1}\)
A
1.32 x \(10^{-6}\)m
B
2.98 x \(10^{-6}\)m
C
3.32 x \(10^{-6}\)m
D
6.82 x \(10^{-6}\)m
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