JAMB - Physics (1993)

1
Which of the following quantities has the same unit as the watt?
คำตอบ
(D)
Force x velocity
2
The external and internal diameter of a tube are measured as (32 ± 2)mm and (21 ± 1)mm respectively. Determine the percentage error in the thickness of the tube.
คำตอบ
(C)
9%
3
Two forces of magnitudes 7N and 3N act at right angles to each other. The angle \(\theta\) between the resultant and the 7N force is given by
คำตอบ
(C)
tan\(\theta\) = \(\frac{3}{7}\)
4
A rocket burns fuel at the rate of 10kgs^-1 and ejects it with velocity of 5 x 10³ms^-1. The thrust exerted by the gas on the rock is
คำตอบ
(B)
5.0 x 10⁴N
5
The force experienced by an object of mass 60.0kg in the moon's gravitational field is 1.002 x 10²N. What is the intensity of the gravitational field?
คำตอบ
(B)
1.67Nkg^-1
6
Which of the following correctly describes the energy changes in the generation of light by a hydroelectric power station?
คำตอบ
(D)
kinetic \(\to\) mechanical \(\to\) electrical \(\to\)light
7
A plane inclined at angle \(\theta\) has a velocity ratio of 10 : 1. The inclination of the plane to the horizontal is given by
คำตอบ
(D)
sin\(\theta\) = \(\frac{1}{10}\)
8
A weightless vessel of dimensions 4m x 3m x 2m is filled with a liquid of density 1000kgm^-3 and sealed. What is the maximum pressure this container can exert on a flat surface? [g = 10ms^-2]
คำตอบ
(D)
2 x 10⁴NM^-2
9
An object of mass 400g and density 600kgm^-3 is suspended with a sting so that half of it is immersed in paraffin of density 900kgm^-3. The tension in the string is
คำตอบ
(B)
3.0N
10
The thermometric properties of the thermocouple is that is
คำตอบ
(A)
e.m.f. changes with temperature
11
A metal rod 800mm long is heated from 10^oC to 95^oC. If it expands by 1.36mm, the linear expansivity of the metal is
คำตอบ
(D)
2.0 x 10^-5K^-1
12
When the volume of a given mass of gas is halved and its temperature doubled, the pressure
คำตอบ
(B)
increases by a factor of 4
13
200g of water at 90°C is mixed with 100g of water at 30°C. What is the final temperature?
คำตอบ
(C)
70^oC
14
The relationship between L and the wavelength I of the stationary wave is
คำตอบ
(D)
4L = 3 \(\lambda\)
15
Determine the distance between the consecutive antinodes XX if the wavelength is 60cm
คำตอบ
(B)
30cm
16
Which of the following waves can propagate through a vacuum?
คำตอบ
(D)
Infra-red waves
17
Radio waves emitted from an antenna are picked up by a radar after reflection from an aircraft in 4 x 10^-3S. How far is the aircraft from the antenna? [c = 3 x 10⁸ms^-1 ]
คำตอบ
(D)
6.0 x 10 ⁵km
18
Which of the following expressions gives the linear magnification produced by a concave mirror of radius of curvature r, if U and V are the object and image distances respectively?
คำตอบ
(B)
\(\frac{2V}{r}\) - 1
19
If the focal length of a camera lens is 20cm, the distance from the film at which the lens must be set to produce a sharp image of an object 100cm away is
คำตอบ
(C)
25cm
20
Which of the following may be used to explain a mirage? i. layers of air near the road surface have varying refractive indices in hot weather. ii. road surfaces sometimes become good reflectors in hot weathers. iii. light from the sky can be reflected upwards after coming close to the road surface.
คำตอบ
(C)
i and iii only
21
A beam of light is incident from air to water at an angle of 30^oC. Find the angle of refraction if the refractive index of water is \(\frac{4}{3}\)
คำตอบ
(C)
22^oC
22
The property of the eye known as its power of accommodation is controlled by the
คำตอบ
(D)
ciliary muscles
23
Which of the following correctly explain(s) why a green leaf appears green in bright day light? i. it absorbs only the green component of sunlight. ii. it absorbs all colour of sunlight except green. iii. it reflects only the green component of sunlight.
คำตอบ
(D)
ii and iii only
24
Which of the following correctly explains why soft iron is proffered to steel in electromagnets? i. soft iron is more readily magnetized than steel. ii. soft iron is more readily demagnetized than steel. iii. soft iron retains magnetism more than steel.
คำตอบ
(C)
i and ii only
25
A current carrying conductor experiences a force when placed in a magnetic field because the
คำตอบ
(B)
magnetic field of the current interacts with external magnetic field
26
A simple cell with mercury-amalgamated zinc electrode prevents
คำตอบ
(A)
local actions
27
The terminal voltage of a battery is 4.0V when supplying a current of 2.0A, and 2.0V when supplying a current of 3.0A. The internal resistance of the battery is
คำตอบ
(C)
2.0\(\Omega\)
28
A current of 100mA passes through a conductor for 2 minutes. The quantity of electricity transported is
คำตอบ
(C)
12C
29
A parallel plate capacitor of area 10cm² in vacuum has a capacitance of 10^-2\(\mu\)F. What is the distance between the plates?(e = 9 x 10^-12fm)
คำตอบ
(B)
9 x 10^-7m
30
A 40-W instrument has a resistance of 90\(\Omega\). On what voltage should it be operated normally?
คำตอบ
(A)
60V
31
Which of the following devices may be used to step up the voltage in a d.c. circuit?
คำตอบ
(D)
an induction coil
32
The primary aim in high tension transmission is to
คำตอบ
(A)
minimize electrical energy losses due to heat production
33
Determine the inductive reactance when a 30.0mH inductor with a negligible resistance is connected to a 1.3 x 10³Hz oscillator.
คำตอบ
(C)
245.0\(\Omega\)
34
Which of the following statements correctly describe(s) cathode rays? i. they consist of tiny particles carrying negative electric charges. ii. they are deflected in a magnetic field but not in an electric field. iii. they consist of fast moving neutrons and deflected in an electric field.
คำตอบ
(A)
i only
35
Natural radioactivity is the random spontaneous disintegration of the nuclei of heavy isotopes of certain elements with the emission of
คำตอบ
(B)
\(\alpha\), \(\beta\) and \(\gamma\)-rays
36
Which of the following are produced after a nuclear fusion process? i. one heavy nucleus. ii. neutrons^-1. iii. protons. iv. Energy.
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(B)
i and iv
37
An element X of an atomic number 88 and mass number 226 decays to form an element Z by emitting two beta particles and an alpha particle. Z is represented by
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(B)
\(^{222}_{88}Z\)
38
The kinetic theory of photoelectron liberated from a metallic surface depends on the
คำตอบ
(D)
frequency of the incident radiation
39
The diagram above shows a velocity time graph representing the motion of a car. Find the total distance covered during the acceleration and retardation of the motion
คำตอบ
(A)
75m
40
In the fig above,A lever of length 200m is used to lift a load of mass 180kg. The pivot at P is 20m from the load. what minimum force F must be applied at the end of the lever [g = 10ms-2]
คำตอบ
(D)
200N