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Physics
WAEC / WASSCE 2013
Electricity and Magnetism
Solution
An electric heater has a resistance of 50\(\Omega\). When it is immersed in water and connected to mains source, it draws a current of 4.0A. Calculate the heat gained by the water if the heater is switched on for 2 minutes, assuming no heat losses to the surroundings
A
4200J
B
1600J
C
24000J
D
96000J
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Q = \(I^2RT\)
= \(4^2\) x 50 x 2 x 60
= 96000J
Source: Myschool Past Questions Archive (Record #35670)
Physics
WAEC / WASSCE 2013
Thermal Physics
Solution
When salt is dissolved in water, the freezing point of the water
A
increases
B
decreases
C
remains the same
D
increases and later decrease
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The salt in the water (same for any other impurities) lowers the freezing point of the solution so that water freezes at a lower temperature.
Source: Myschool Past Questions Archive (Record #35671)
Physics
WAEC / WASSCE 2013
Waves and Optics
Solution
The equation of a certain progressive transverse wave is y = 2 sin 2 \(\pi ( \frac{t}{0.01} - \frac{x}{30})\), where x and y are in cm and t in seconds. Calculate the period of the wave.
A
0.001s
B
0.010s
C
10.000s
D
100.000s
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Compare: Y = 2 sin 2 \(\pi (\frac{t}{0.01} - \frac{x}{30})\)
with the wave equation,
y = A sin 2 \(\pi (\frac{t}{T} - \frac{x}{\lambda}\))
⇒ \(\frac{t}{T} = \frac{t}{0.01}\)
T = 0.010s
Source: Myschool Past Questions Archive (Record #35672)
Physics
WAEC / WASSCE 2013
Waves and Optics
At which position should an object be placed in front of a concave mirror in order to obtain an image which is of the same size as the object?
A
at the centre of curvature
B
at the principal focus
C
between the pole and principal focus
D
between the centre of curvature and principal focus
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #35673)
Physics
WAEC / WASSCE 2013
Waves and Optics
Solution
Images formed by a convex mirror are always
A
magnified
B
behind the mirror
C
real
D
inverted
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Convex mirrors always form virtual images, which appear behind the mirror.
Source: Myschool Past Questions Archive (Record #35674)
Physics
WAEC / WASSCE 2013
Heat Energy & Temperature
Solution
The refractive index of a material is 1.5. Calculate the critical angle at the glass-air interface
A
19o
B
21o
C
39o
D
42o
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Sin C = \(\frac{1}{\eta} = \frac{1}{1.5} = 0.6667\)
C = sin\(^{-1}\) 0.6667
= 42^\circ
Source: Myschool Past Questions Archive (Record #35675)
Physics
WAEC / WASSCE 2013
Thermal Physics
Solution
Which of the following radiations has it's frequency lower than that of infrared radiation?
A
Utra-violet rays
B
gamma rays
C
x-rays
D
radio waves
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Radio waves have lower frequencies compared to infrared radiation, while ultraviolet rays, gamma rays, and x-rays have higher frequencies.
Source: Myschool Past Questions Archive (Record #35680)
Physics
WAEC / WASSCE 2013
Waves and Optics
Solution
A string under tension produces a note of frequency 14Hz. Determine the frequency when the tension is quadrupled.
A
14Hz
B
18Hz
C
28Hz
D
56Hz
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
The formula for the frequency in a stringed instrument : \(f = \frac{1}{2} \sqrt{\frac{T}{m}}\)
f = frequency; T = tension in the string; m = mass per unit lenth of the string.
f\(_1\) = 14 = \(\frac{1}{2} \sqrt{\frac{T}{m}}\).
When T is quadrupled, we have
f\(_2\) = new frequency = \(\frac{1}{2} \sqrt{\frac{4T}{m}}\)
= 2(\(\frac{1}{2} \sqrt{\frac{T}{m}}\))
= 2 f\(_1\)
= 2 x 14
= 28 Hz
Source: Myschool Past Questions Archive (Record #35682)
Physics
WAEC / WASSCE 2013
Waves and Optics
Which of the following statements about waves in pipes is correct?
A
for open pipes, there is only one end correction to be accounted for
B
for closed pipes, there are two end corrections to be accounted for
C
only odd harmonics are possible in closed pipes
D
all harmonics are possible in closed pipes
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #35685)
Physics
WAEC / WASSCE 2013
Electricity and Magnetism
When a person holds a negatively charges metal rod and stands bare-footed on the ground, how will the charges leak?
A
negative charges flows to the ground through the person's body
B
positive charges flow from the ground through his body to neutralize the negative charges
C
positive charges in the air neutralizes the negative charges the person is holding
D
negative charges will leak through the air
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #35686)
Physics
WAEC / WASSCE 2013
Mechanics and Properties of Matter
Solution
A charge of 2.0 x 10\(^{-5}\) C experiences a force of 80N in a uniform electric field. Calculate the magnitude of the electric field intensity
A
8.0 x 106 NC-1
B
4.0 x 106 NC-1
C
4.0 x 104 NC-1
D
2.0 x 104 NC-1
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
E = \(\frac{F}{Q} = \frac{80}{2 \times 10^{-5}}\)
= 4 x 10\(^6\) NC\(^{-1}\)
Source: Myschool Past Questions Archive (Record #35691)
Physics
WAEC / WASSCE 2013
Heat Energy & Temperature
Solution
A potential difference of 12V is applied across the ends of a 6\(\Omega\) resistor for 10 minutes. Determine the quantity of heat generated
A
720J
B
1200J
C
14400J
D
43200J
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Q = \(\frac{V^2 t}{R}
= \frac{12^2 \times 10 \times 60}{6}\)
= 14400J
Source: Myschool Past Questions Archive (Record #35694)
Physics
WAEC / WASSCE 2013
Mechanics and Properties of Matter
Which of the following instruments is used to determine the accurate value of the electromotive force of a cell?
A
voltmeter
B
meterbridge
C
voltameter
D
potentiometer
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #35696)
Physics
WAEC / WASSCE 2013
Electricity and Magnetism
Solution
The capacitance of parallel plates capacitors varies
A
inversely as the square of the distance between the plates
B
directly as the square of the distance between the plates
C
inversely as the distance between the plates
D
directly as the distance between the plate
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
capacitance C is the ability of the capacitor to store charges. and it depends on the size A, shape, and separation d of the conductors and the material separating them ε
C = \(\frac{εA}{d}\)
C is inversely proportional to d.
Source: Myschool Past Questions Archive (Record #35700)
Physics
WAEC / WASSCE 2013
Electricity and Magnetism
Solution
Which of the following devices does not makes use of eddy current for its action? A/An
A
galvanometer
B
speedometer
C
induction furnace
D
induction coil.
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
an induction coil is used to create high potential differences from sources of low potential differences. it does not make of Eddy's current for its action.
Source: Myschool Past Questions Archive (Record #35703)