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Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
An image which can be formed on a screen is said to be
A
virtual
B
blurred
C
inverted
D
erect
E
real
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #33405)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
The saturation vapour of a liquid depends on its
A
volume
B
temperature
C
mass
D
density
E
pressure
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 #33314)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
Diagram
Which of the following statements is true of the diagram shown above?
Attached Figure / Diagram
A
the two point, A and B are in phase
B
distance AB is halgf the wavelength of the wave
C
AC and BD are the amplitude of the wave
D
the two points A and B represents the wave crests
E
the wave has four crests
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 #33415)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
Which of the following statements is not correct? Isotopes of an element have
A
the same number of electric charges on the nucleus
B
the same chemical properties
C
different nucleon numbers
D
different proton numbers
E
different atomic masses
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 #33446)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
Solution
Two objects of masses 80kg and 50kg are separated by a distance of 0.2m. If the gravitational constant is 6.6 x 10-11Nm kg, calculate the gravitational attraction between them.
A
4.9 x 10-9N
B
1.3 x 10-6N
C
6.6 x 10-8N
D
6.6 x 10-6N
E
2.6 x 10-9N
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
F = \(\frac{Gm_1m_2}{r^2} = \frac{6.6 \times 10^{-11} \times 80 \times 50}{0.2 \times 0.2}\)
= 6.6 x 10-6N
Source: Myschool Past Questions Archive (Record #33424)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
Diagram
Solution
Using the data in the circuit illustrated above, calculate the value of R
Attached Figure / Diagram
A
0.02\(\Omega\)
B
0.05\(\Omega\)
C
5.00\(\Omega\)
D
20.00\(\Omega\)
E
50.00\(\Omega\)
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
R = \(\frac{V}{T} = \frac{2v}{40 \times 10^{-3}}\)
= 50.00\(\Omega\)
Source: Myschool Past Questions Archive (Record #33433)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
Which of the following has the highest surface tension?
A
cold water
B
soapy water
C
warm water
D
oily water
E
salty water
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 #33458)
Physics
WAEC / WASSCE 1991
Heat Energy & Temperature
Solution
(a)(i) By means of a labelled diagram, describe the mode uf operation of a modern X-ray tube.
(ii) State the energy transformation which takes place during the operation.
(b) Explain the terms hardness and intensity as applied to X-rays
(c)(i) State three uses of X-rays
(ii) State one hazard of over-exposure to X-rays in a radiological laboratory, indicating two safety precautions.
A
cold water
B
soapy water
C
warm water
D
oily water
E
salty water
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
(a)(i)
Mode of Operation:
In the X-ray tube a Low voltage high p.d is applied between the hot cathode and the anode. Electrons are emitted from the cathode and are accelerated to an extremely high speed. They are suddenly decelerated when they strike the anode causing the emission of high - energy radiation of short wavelength - X-ray. In this process the anode becomes very hot, and requires cooling fins on the outside of the tube.
Energy Transformation: The electrons have kinetic energy which is partly changed to internal energy (potential) and finally changed to heat energy.
(b) Hardness: Refers to X-rays with high penetrating power, short wavelength but high frequency. They are produced by increasing the p.d. between the cathode and anode. Such X-rays are called hard X-rays. Less penetrating or lower frequency ones are called soft X-rays. They are produced at lower p.d.
Intensity: High intensity X-rays beam results from the increase of current through the filament which leads to increase in the number of electrons.
(c)(i) Uses of X-rays:
(1) Investigating the structure of crystals ; (2) X-ray examination of the body for broken bones; (3) As invincible bullets for the treatment of tumours ; (4) Examination of metals for defects and fractures.
(ii) They may cause damage to living tissue and to cells. Precaution to be taken includes lead screening and regular health checks.
Source: Official Exam / Past Question Archive
Physics
UTME / JAMB 1991
Heat Energy & Temperature
Diagram
Solution
Find the tension T\(_1\) in the diagram above if the system is in equilibrium [G = 10ms\(^{-2}\)]
Attached Figure / Diagram
A
200/√3N
B
100/√3N
C
300/√3N
D
100N
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
The diagram transforms into the one above:
Tan 30º = \(\frac{\text{opp}}{\text{adja}}\) = \(\frac{T_1}{100}\)
But tan 30º = \(\frac{1}{\sqrt{3}}\)
\(\frac{1}{\sqrt{3}}\) = \(\frac{T_1}{100}\)
T\(_1\) = \(\frac{100}{\sqrt{3}}\)N
Source: Myschool Past Questions Archive (Record #41696)
Physics
UTME / JAMB 1991
Heat Energy & Temperature
Diagram
Solution
The net capacitance of the circuit shown above is
Attached Figure / Diagram
A
8.0µF
B
6.0µF
C
4.0µF
D
2.0µF
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Capacitance in parallel.
\(C_4 = C_1 + C_2\) = 2 + 2 = 4µf.
\(\frac{1}{C_T} = \frac{ 1}{C_3} + \frac{1}{C_4}\)
= \(\frac{ 1}{4} + \frac{1}{4}\)
= \(\frac{ 1 + 1}{4}\)
\(\frac{1}{C_T} = \frac{2}{4}\)
\(C_T = \frac{4}{2}\) = 2µf.
Source: Myschool Past Questions Archive (Record #41699)
Physics
UTME / JAMB 1990
Heat Energy & Temperature
Solution
Which of the following statements are correct? i. land and sea breezes are natural convection currents. ii. convection may occur in liquids or gasses but not in solids. iii. the vacuum in a thermos flask prevents heat loss due to convection only.
A
i and ii only
B
i and iii only
C
i and iii only
D
i, ii, and iii
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
real-life examples of convection:
Breeze. The formation of sea and land breeze form the classic examples of convection.
Boiling Water.
Blood Circulation in Warm-Blooded Mammals.
Air-Conditioner.
Radiator.
Refrigerator.
The vacuum between the two walls prevents heat being transferred from the inside to the outside by conduction and convection.
Source: WAEC / JAMB / NECO Classroom Archive (Record #28248)
Physics
WAEC / WASSCE 1990
Heat Energy & Temperature
Which of the following instruments is suitable for making the most accurate measurement of the internal diameter of a test tube?
A
metre rule
B
A pair of callipers
C
A micrometer screw gauge
D
A tape rule
E
A set square
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 #24080)
Physics
WAEC / WASSCE 1990
Heat Energy & Temperature
Solution
A simple pendulum makes 50 oscillations in one minute. What is its period of oscillation?
A
0.02s
B
0.20s
C
0.83s
D
1.20s
E
50.00s
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
T = t/no. of oscillation = 1 x 60/50 = 1.2s
Source: Myschool Past Questions Archive (Record #24090)
Physics
WAEC / WASSCE 1990
Heat Energy & Temperature
Diagram
Solution
The body P shown in the diagram above is in equilibrium. If the mass Q of the body is 10kg, calculate the tension T in the string. (Take g = 10ms2)
Attached Figure / Diagram
A
20/√3N
B
20N
C
50N
D
200√3N
E
200N
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
T = P/cos60o = 100/cos60o = 200N
Source: Myschool Past Questions Archive (Record #24091)
Physics
WAEC / WASSCE 1990
Heat Energy & Temperature
Diagram
The diagram above represents a portion of a micrometer screw 20 gauge. What is its reading?
Attached Figure / Diagram
A
3.70mm
B
3.67mm
C
3.50mm
D
3.33mm
E
3.17mm
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #24085)