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Physics
WAEC / WASSCE 1999
Heat Energy & Temperature
Diagram
Solution
Using the diagram above, calculate the effective capacitance of the circuit
Attached Figure / Diagram
A
1.56μf
B
3.00μF
C
3.71μF
D
9.00μF
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
\(C_1\) = 3\muF + 4\muF = 7\muF ( capacitance in parallel )
\(\frac{1}{ C} = \frac{ 1}{2} + \frac{1}{7} = \frac{ 7 + 2 }{14} = \frac{9}{14}\)
∴ C = \(\frac{14}{9}\) = 1.56\muF
Source: Myschool Past Questions Archive (Record #25498)
Physics
WAEC / WASSCE 1999
Heat Energy & Temperature
Solution
Measure and record the e.m.f of the accumulator provided. Connect the circuit as shown in the diagram. With zero resistance in the resistance box, adjust the rheostat to obtain the maximum possible reading on the ammeter. Do not adjust the rheostat again throughout the experiment. Open the key. With R= 1\(\Omega\), close the key, read and record the reading of the ammeter I. Calculate 1\(^{-1}\) Repeat the experiment for R=2,3,4 and 5\(\Omega\) respectively. In each case, read and record the value of \(1_A\) and calculate the Corresponding value of l\(_{A}^{-1}\). Now connect the resistor Q in series into the circuit and without altering the setting of the rheostat, record the new ammeter readings \(l_B\) for R= 1,2,3, 4, and 5\(\Omega\). Calculate the corresponding value of \(l_B\) in each case. Tabulate all your readings. On the same graph and using the same axes and scales, plot the graphs of:
(i) I\(_{A}^{-1}\)' on the vertical axis and R on the horizontal axis;
(ii) l\(_{B}^{-1}\) on the vertical axis and R on the horizontal axis. Calculate the slopes \(S_A\) in (i) and \(S_B\) in (ii) above. Determine the difference D between the intercepts of the graphs on the vertical axis. State two precautions taken to ensure accurate results.
(b) i. Explain why a battery of eight dry Leclanche cells, each of e.m.f. 1.5v is not normally used in place of a motor-car battery of 12V to start a car.
ii. State two sources of e.m.f. other than the chemical cell.
A
Radioactive materials are stored in glass casings
B
Radioactive materials are handled with remote-controlled tongs
C
Technicians in nuclear stations wear radio-sensitive badges which are checked regularly.
D
Radioactive materials are kept in thick-walled lead containers
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Table of values/observation
S/N
R(\(\Omega\))
\(I_A\)(A)
I\(^{-1}_{A}\)
\(I_B\)(A)
I\(^{-1}_{B}\)(A\(^{-1}\))
1
1.00
1.80
0.556
0.95
1.053
2
2.00
0.95
1.053
0.60
1.667
3
3.00
0.60
1.667
0.50
2.000
4
4.00
0.45
2.222
0.40
2.500
5
5.00
0.40
2.500
0.35
2.857
Slop\(e_A\) (\(s_A\)) = \(\frac{2.5-0.25}{5-0.35} = \frac{2.25}{4.65}\) = 0.4838\(\Omega ^{-1}\) A\(^{-1}\)
Slop\(e_B\) (\(S_B\)) = \(\frac{2.85-0.95}{5-0.55}\) = \(\frac{1.9}{4.45}\) = 0.4270\(\Omega ^{-1} A^{-1}\)
Interpret on I\(_{A}^{-1}\) (A\(^{-1}\)) axis = 0.075A\(^{-1}\)
Interpret on I\(_{B}^{-1}\) (A\(^{-1}\)) axis = 0.725A\(^{-1}\)
= D = \(S_B\) - \(S_A\)
= 0.725 - 0.075 = 0.65A\(^{-1}\)
Precautions:
- Always open the key when readings are not taken.
- Ensure tight connections.
(b)i. The current produced by the cells is less than that of the car battery because of the total internal resistance of the cells. A car requires a large amount of Current to start it. This amount of current cannot be supplied by the cells
ii. Photocell and Dynamo
Source: Official Exam / Past Question Archive
Physics
WAEC / WASSCE 1999
Heat Energy & Temperature
I. All elements emit and absorb characteristic spectra. II. Spectral analysis is an important method of identifying environmental pollutants. III. The chemical composition of stars could be determined using spectral analysis. Which of the statements above are correct?
A
I, II and III
B
II and III only
C
I and III only
D
I and II only
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 #25510)
Physics
WAEC / WASSCE 1999
Heat Energy & Temperature
Solution
A stone is projected horizontally from the top of a tower with a speed of 5ms-1. It lands on the ground level at a horizontal distance of 20m from the foot of the tower. Calculate the height of the tower. (g = 10ms\(^{-2}\))
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
H = \(\frac{1}{2} gt^2\) S = ut
t = \(\frac{5}{u} = \frac{20}{5} = 45\)
H = \(\frac{1}{2}gt^2 = \frac{1}{2} \times 10 x 4^2\)
= 80m
Source: Myschool Past Questions Archive (Record #54657)
Physics
WAEC / WASSCE 1999
Heat Energy & Temperature
Solution
(a) Define Young's modulus.
(b) State the physical quantities one has to measure in order to determine the Young's modulus of a wire.
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
(a) Young's Modulus is the ratio of tensile stress to tensile strain
(b) Length of wire, extension of wire, load used, diameter of wire.
Source: Myschool Past Questions Archive (Record #54661)
Physics
WAEC / WASSCE 1999
Heat Energy & Temperature
Which of the following is not a safety precaution in a nuclear station?
A
Radioactive materials are stored in glass casings
B
Radioactive materials are handled with remote-controlled tongs
C
Technicians in nuclear stations wear radio-sensitive badges which are checked regularly.
D
Radioactive materials are kept in thick-walled lead containers
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 #25516)
Physics
WAEC / WASSCE 1998
Heat Energy & Temperature
Solution
A waterfall is 1260m high. Calculate the change in temperature of a quantity of water that falls from the top to the bottom of the waterfall. (Neglect heat losses to the surroundings, take g as 10m-2 and specific heat capacity of water as 4200Jkg-1K-1)
A
0.3oC
B
3.0oC
C
33.3oC
D
42.0oC
E
100.0oC
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
\(\Delta t = \frac{gh}{c} = \frac{1260 \times 10}{4200}\)
= 3.0o
Source: WAEC / JAMB / NECO Classroom Archive (Record #33586)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
Solution
In the AC circuit diagram above, the resonance frequency is
A
5000π Hz
B
2500π Hz
C
5000/π Hz
D
2500/π Hz
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
resonance frequency \(f_r\) = \(\frac{ 1}{ 2\pi \sqrt{LC}}\)
\(f_r\) = \(\frac{1}{2\pi \sqrt{5\times10^{-6} \times 8\times 10^{-3}}}\)
\(f_r\) = \(\frac{1}{ \pi 0.0004}\)
\(f_r\) = \(\frac{ 2500}{\pi}\)
Source: Official Exam / Past Question Archive
Physics
UTME / JAMB 1998
Heat Energy & Temperature
Solution
The physical quantity that has the same dimensions as impulse is
A
energy
B
momentum
C
surface tension
D
pressure
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Impulse = F x t = m(v-u)
Source: Myschool Past Questions Archive (Record #27582)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
Solution
In free fall, a body of mass 1kg drops from a height of 125m from rest in 5s. How long will it take another body of mass 2kg to fall from rest from the same height? [g = 10ms-1·]
A
5s
B
10s
C
12s
D
15s
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
In free fall, every object will reach the ground at same time
Source: Myschool Past Questions Archive (Record #27586)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
Solution
The linear expansivity of brass is 2 x 10-5C-1. If the volume of a piece of brass is 15.00cm3 at 00C, What is the volume at 100oC?
A
16.03cm3
B
16.00cm3
C
15.09cm3
D
15cm3
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
linear expansivity = \(\frac {V_2 - V_1}{V_1 {\times} {\Delta}{\theta}}\)
3 x 2 x 10-5 =\(\frac {V_2 - 15}{15 {\times} (100 - 0)}\)
V2 = 15.09cm3
Source: Myschool Past Questions Archive (Record #27621)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
A vapour is said to be saturated when
A
more molecules return to the liquid than the amount that left it
B
a dynamic equilibrium exists between the molecules of the liquid and the vapour molecules at a given temperature
C
the vapour pressure is equal to the atmospheric pressure
D
all molecules are moving with the same speed in all directions at a given temperature
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 #27635)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
One valid assumption of the kinetic theory of gasses is the
A
the molecules of a gas are constantly in a state of motion and the number of collision remains constant
B
the number of molecule of gas increases with increasing pressure
C
as the temperature increases, the number of collision made by the gas molecule remains constant
D
the molecules of gas are all identical and are very small in size
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 #27637)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
In a closed organ pipe producing a musical note, an antinode will always be produced at
A
the closed end
B
the open end
C
the middle
D
all the parts of the pipe
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 #27640)
Physics
UTME / JAMB 1998
Heat Energy & Temperature
Solution
The displacement d produced in a glass block of thickness t and refractive index n when an object is viewed through it is
A
t – n
B
t (1 + 1/n)
C
t (1-1/n)
D
t (1/n - 1)
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
n = \(\frac {\text{real depth}}{\text {apparent depth}{}}\)
n = \(\frac {t}{t-d}\)
\(\frac{t - d}{1}\) = \(\frac{t}{n}\)
-d = \(\frac{t}{n}\) - t
d = - \(\frac{t}{n}\) + t
d = t - \(\frac{t}{n}\)
d =t (1 - \(\frac{1}{n}\))
Source: Myschool Past Questions Archive (Record #27653)