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1999 - JAMB Physics Past Questions and Answers - page 3

21

A 3000W electric cooker is to be used on a 200V mains circuit. Which of the fuses below can be used safely with the cooker?

A
2A
B
5A
C
10A
D
20A
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22

A galvanometer has a resistance of 5Ω. By using a shunt wire of resistance 0.05Ω, the galvanometer could be converted to an ammeter capable of reading 2Amp. What is the current through the galvanometer?

A
2mA
B
10mA
C
20mA
D
25mA
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23

In fleming's right-hand rule, the thumb, the forefinger and the middle finger if held mutually at right angles represent respectively, the

A
motion, the field and the induced current
B
induced current, the motion and the field
C
field, the induced current and the motion
D
induced current, the field and the motion
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24

At what frequency would a 10H inductor have a reactance of 2000Ω?

A
π/200Hz
B
π/100Hz
C
100/πHz
D
100πHz
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25

The core of an efficient transformer should consist of laminated pieces of metal in order to

A
increase the heat produced by increasing the eddy current
B
increase the heat produced by reducing the eddy current
C
reduce the heat produced by increasing the eddy current
D
reduce the heat produced by reducing the eddy current
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26

Gamma rays are produced when

A
high velocity electrons are abruptly stopped in metals
B
energy changes occur within the nucleus of atoms
C
energy changes occur within the electronic structure of atoms
D
electrons are deflected in very strong magnetic fields
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27

What is the speed of a particle of mass 10-27kg whose wavelength is 10-8m.

[h = 6.63 x 10-34Js]

A
6.63ms-1
B
66.30ms-1
C
663.00ms-1
D
6630.00ms-1
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28

in a series R-L-C circuit at resonance, the voltages across the resistor and the inductor are 30V and 40V respectively, what is the voltage across the capacitor?

A
30V
B
40V
C
50V
D
70V
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29

In the Rutherford scattering experiment, a beam of alpha particles was fired at a thin gold film with some of the particles being considerably deflected. This shows that

A
a gold nucleus contains protons, neutrons and electrons uniformly distributed in a tiny volume
B
the gold nucleus is positively charged and is concentrated in a tiny volume
C
the gold nucleus emitted alpha particles
D
the gold nucleus is concentrated in a tiny volume and contains alpha particles
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30

2311Na + Proton → pqX + alpha particle

What are the values of p and q respectively in the equation above?

A
10 and 20
B
12 and 24
C
20 and 10
D
24 and 12
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