2006 - WAEC Physics Past Questions and Answers - page 4

31
A ray from a fixed object is incident on a plane mirror at an angle of 20o. If the mirror is rotated through 30o by how many degree would the reflected ray rotate?
A
60o
B
50o
C
40o
D
30o
correct option: a
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32
Which of the following distances is usually adjustable in the camera? The distance between the
A
lens and the film
B
diaphragm and the shutter
C
shutter and the film
D
diaphragm and the film
correct option: b
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33
A travelling microscope is focused on a mark on a table. If a glass block of thickness 18.0cm is placed on the mark by how many centimeters will the microscope be moved upwards so as to focus the mark once again? [refractive index of glass = 1.5]
A
27cm
B
24cm
C
9cm
D
6cm
correct option: d
Apparent depth = \(\frac{\text{thickness}}{\text{refractive index}}\)

= \(\frac{18}{1.5} = 12cm\)

Upward adjustment = 18 - 12

= 6cm
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34
In which of the following media would sound wave travel fastest?
A
wood
B
water
C
iron
D
mercury
correct option: c
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35
Which of the following actions is necessary in order to tune a string to produce a note of an octave higher than its fundamental?
A
doucling the length of the string
B
reducing the tension by half
C
reducing the mass per unit length
D
increasing the tension four times
correct option: b
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36
The acceleration due o gravity may be defined as the force
A
of attraction of the sun and on the earth
B
with which the earth revolves around the sun
C
with which the earth attracts one kilo-gram mass
D
of the moon on the earth
correct option: c
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37
An electron of mass m and charge \(\Box\) enters a uniform electric field between two metal plates P and q separated by a distance d. P is maintained at a potential V while Q is earthed. Determine an expression for the magnitude of the acceleration of electron through the field
A
\(\frac{eV}{md}\)
B
\(\frac{d}{meV}\)
C
\(\frac{md}{eV}\)
D
\(\frac{e}{Vmd}\)
correct option: a
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38
Which of the following factors does not affect the capacitance of a parallel plate capacitor?
A
area of the plates
B
nature of the surface of the plates
C
distance of separation between the plates
D
nature of the insulating material between the plates
correct option: b
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39
The equivalent capacitance of a 3\(\mu F\) capacitor and a 6\(\mu F\) capacitor connected in parallel is
A
2.0\(\mu F\)
B
3.0\(\mu F\)
C
4.5\(\mu F\)
D
9.0\(\mu F\)
correct option: d
C = C1 + C2

= 3 + 6 = 9\(\mu F\)
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40
a cell of e.m.f. 1.5V and internal resistance 1.0\(\Omega\) is connected to two resistor of resistance 2.0\(\Omega\) and 3.0\(\Omega\) in series. Calculate the current through the resistors
A
0.25A
B
0.30A
C
0.35A
D
0.50A
correct option: a
I = \(\frac{E}{R + r} = \frac{1.5}{5 + 1}\)

= \(\frac{1.5}{6} = 0.25A\)
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