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Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
The diagram above illustrates a structure of a typical photocell.
(i) Identify each of the parts labelled A and B.
(ii) State one function each of A and B
(iii) Einstein’s photoelectric equation can be written as E = hf – Wo. State what each of the terms E, hf and Wo represent.
(b) A photon is incident on a metal whose work function is 1.32 eV. An electron is emitted from the surface with a maximum kinetic energy of 1.97 eV. Calculate the frequency of the photon. [1 eV = 1.6 x 10-19 J]
(c)(i) Define half-life of a radioactive element.
(ii) Sketch a graph of the relation N = Noe-\lambdat and indicate the half-life.
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
The expected answer is:
(a) (i) Identification of labelled parts of photocell
A - Emitter / cathode
B - Collector / anode
(ii) Function of part of photocell
A - emits electrons
B - attracts electrons
(iii) Meaning of terms in Einstein’s photoelectric equation
E - kinetic energy of photoelectrons
hf - energy of incident photon
Wo - work function of metal
Source: Myschool Past Questions Archive (Record #56612)
Physics
WAEC / WASSCE 2019
Heat Energy & Temperature
Which of the following quantities is a vector?
A
Volume
B
Momentum
C
Energy
D
Speed
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #58780)
Physics
WAEC / WASSCE 2019
Electricity and Magnetism
The induced current in a coil always flows in a direction so as to oppose the change that causes it. This statement is known as
A
Coulomb's law
B
Lenz's law
C
Faraday's law
D
Ampere's law
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #58785)
Physics
WAEC / WASSCE 2019
Electricity and Magnetism
Which of the following instruments can be used to compare the magnitudes of charges on two given bodies?
A
Electrophorus
B
Ebonite rod
C
Gold-leaf electroscope
D
Proof planes
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 #58787)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
A body of mass 2 kg is released from a point 100 m above the ground. Calculate its kinetic energy 80m from the point of release.
A
1600 J
B
900 J
C
600 J
D
200 J
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
K.E = mgh
but h = 80m, m = 2kg, g = 10m/s^2
K.E = 2 x 10 x 80 = 1600J.
Source: Myschool Past Questions Archive (Record #58793)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
The time rate of increase in velocity is called
A
force
B
momentum
C
acceleration
D
speed
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 #58778)
Physics
WAEC / WASSCE 2019
Waves and Optics
Which of the following waves is not mechanical?
A
Waves in pipes
B
Water waves
C
Radio waves
D
Sound waves
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 #58800)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
A loaded spring is set in simple harmonic motion. The force that tends to restore the load to its equilibrium position is
A
adhesive
B
elastic
C
frictional
D
gravitational
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Elastic Force: This is the force exerted by the spring when it is compressed or stretched. It is the elastic force that directly acts to restore the spring to its equilibrium position.
Source: Myschool Past Questions Archive (Record #58801)
Physics
WAEC / WASSCE 2019
Waves and Optics
Which of the following cases cannot produce total internal reflection? A light ray travelling from
A
glass to water
B
kerosene to air
C
air to water
D
water to ice
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 #58805)
Physics
WAEC / WASSCE 2019
Thermal Physics
Solution
The vacuum in a thermoflask reduces heat loss resulting from
A
radiation only
B
conduction and convection only
C
radiation and convection only
D
conduction only
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The vacuum of a thermos flask prevents heat loss by conduction and convection, conduction because vacuum is a poor conductor of heat, convention because
the space between the walls is a vacuum which reduces the heat loss due to conduction and convection. if there is any atmospheric air or material between then there will be some amount of heat transfer through the conduction and convection
Source: Myschool Past Questions Archive (Record #58807)
Physics
WAEC / WASSCE 2019
Thermal Physics
Solution
Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 ^\circC to 80 ^\circC. [specific latent heat of fusion of ice= 3.36 x 10\(^5\) Jkg\(^{-1}\) specific heat capacity of water 4.2 x 10\(^3\) J kg\(^{-1}\) K\(^{-1}\)]
A
4.80 kJ
B
20.16 kJ
C
40.32 kJ
D
22.17 kJ
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Heat needed to change 60g (0.06kg) of ice at 0\(^o\)C to water at 0\(^o\)
= 0.06 x 3.36 x 10\(^5\)J
= 0.2016 x 10\(^5\) J
Heat required to raise the temp. of 60g (0.06kg) of water from 0\(^o\)C to 80\(^o\)C
= 0.06 x 4.2 x 10\(^3\) x (80.0)J
= 0.06 x 4.2 x 10\(^3\) x 80
= 20.16 x 10\(^3\)
= 0.2016 x 10\(^5\)
Total heat needed = (0.2016 + 0.2016) 10\(^5\)J
= 0.4032 x 10\(^5\) J
= 40.32KJ
Source: Myschool Past Questions Archive (Record #58857)
Physics
WAEC / WASSCE 2019
Thermal Physics
Solution
The wire of a platinum resistance thermometer has d resistance of 3.5\(\Omega\) at 0 ^\circC and 10.52\(\Omega\) at 100^\circC. Calculate the temperature of the wire when its resistance is 7.5\(\Omega\).
A
78 °C
B
25 \(^o\)C
C
30\(^o\)C
D
57 \(^o\)C
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Using the formula
t = \(\frac{R - R_0}{R_{(100)} - R_0} \times 100^oC\)
t = \(\frac{7.5 - 3.5}{10.5 - 2..5} \times 100^oC\)
= \(\frac{4}{7} \times 100\)
= 57.14\(^o\)C
~ 57\(^o\)C
Source: Myschool Past Questions Archive (Record #58861)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
A transverse pulse of frequency 9 Hz traves 4.5m in 0.6 s. Calculate the wavelength of the pulse.
A
3.33 m
B
0.30 m
C
0.83 m
D
1.20 m
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Wavelength (\(\alpha\)) = \(\frac{Velocity (V)}{Frequency (f)}\)
Velocity = \(\frac{Distance}{Time}\) = \(\frac{4.5}{0.6}\)
= \(\frac{7.5}{9.0}\)
= 0.83m
Source: Myschool Past Questions Archive (Record #58863)
Physics
WAEC / WASSCE 2019
Waves and Optics
In which of the following media is the speed of sound the least?
A
Air
B
Brass
C
Water
D
Wood
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 #58885)
Physics
WAEC / WASSCE 2019
Heat Energy & Temperature
Which of the following statements about a moving object is correct?
A
When accelerating, the resultant force acting on it must be equal to zero.
B
There must always be a non-zero resultant force acting on it.
C
At a steady velocity, the resultant force acting on it must be equal to zero
D
At a steady velocity, the air resistance must be equal to zero.
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 #58822)