JAMB - Physics (2000)

1
When a ship sails from salt water into fresh water, the fraction of its volume above the water surface will
پاسخ دهید
(B)
decrease
2
I. Its velocity is constant
II. No work is done on the body
III. It has constant acceleration directed away from the centre
IV. The centripetal force is directed towards the centre

Which combination of the above is true of a body moving with constant speed in a circular track?
پاسخ دهید
(A)
II and IV
3
The velocity ratio of a machine is 5 and its efficiency is 75%. What effort would be needed to lift a load of 150N with the machine?
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(C)
40N
4
At a fixed point below a liquid surface, the pressure downwards is P1 and pressure upwards is P2. It can be deduced that?
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(D)
P₁ = P₂
5
If the force and the velocity on a system are each reduced simultaneously by half, the power of the system is
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(B)
reduced to a quarter
6
A catapult used to hold a stone of mass 500g is extended by 20cm with an applied force F. If the stone leaves with a velocity of 40m/s, the value of F is
پاسخ دهید
(C)
4.0 x 10³N
7
A stream is flowing at 0.75ms\(^{-1}\) and a boat heading perpendicular for the stream landed at the opposite bank at an angle of 30°. Calculate the velocity of the boat.
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(A)
1.50ms^-1
8
A rope is being used to pull a mass of 10kg vertically upward. Determine the tension in the rope if, starting from rest, the mass acquires a velocity of 4ms\(^{-1}\) in 8s [g = 10ms\(^{-2}\)]
پاسخ دهید
(D)
105N
9
I. The frictional force is independent of the area of the surfaces in conduct
II. The frictional force depends on the nature of the surfaces in contact
III. The frictional force depends on the speed of sliding
IV. The frictional force is directly proportional to the normal reaction.

Which combination of the above is true of sliding friction?
پاسخ دهید
(B)
I, II and IV
10
Total internal reflection occurs when light moves from?
پاسخ دهید
(A)
a dense medium to a less dense medium
11
A quantity of water at 0°C is heated to about 30°C. At each degree rise in temperature, its density will
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(D)
rise then fall
12
I. Coherence
II. Same frequency
III. Same wavelength
IV. Same Intensity

Which of the conditions above are necessary to produce interference fringes?
پاسخ دهید
(C)
I, II and III
13
A boy observes a piece of stone at the bottom of a river 6.0m deep. If he looks from the surface of the river, what is the apparent distance of the stone from him? [Refractive Index of Water = 4/3]
پاسخ دهید
(D)
4.5m
14
A thin wire with heavy weights attached to both ends is hung over a block of ice resting on two supports. If the wire cuts through the ice block while the block remains solid behind the wire, the process is called
پاسخ دهید
(C)
regelation
15
Dry
Day 1 - 30°C | Day 2 - 29°C | Day 3 - 25°C

Wet
Day 1 - 22°C | Day 2 - 22°C | Day 3 - 21°C

The reading above are for three consecutive days from a wet and dry bulb hygrometer. It can be concluded that the relative humidity for the three days
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(C)
increased steadily
16
One end of a long wire is fixed while a vibrator is attached to the other end. When the vibrator is energized, the types of waves generated in the wire are
پاسخ دهید
(A)
stationary and longitudinal
17
A metal of mass 0.5kg is heated to 100°C and then transferred to a well-lagged calorimeter of heat capacity 80JK^-1 containing water of heat capacity 420JK^-1 at 15°C. If the final steady temperature of the mixture is 25°C, find the specific heat capacity of the metal.
پاسخ دهید
(C)
133Jkg^-1K^-1
18
The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by
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(A)
convection
19
A radio is operated by eight cells each of e.m.f. 2.0V connected in series. If two of the cells are wrongly connected, the net e.m.f. of the radio is
پاسخ دهید
(C)
12V
20
If a charged ion goes through combined electric and magnetic fields, the resultant emergent velocity of the ion is
پاسخ دهید
(A)
E/B
21
A projection lantern is used to give the image of a slide on a screen. If the image is 24 times as large as the slide and the screen is 72.0m from the projecting lens, what is the position of the slide from the lens?
پاسخ دهید
(B)
3.0m
22
An electron of charge 1.6 x 10^-19C and mass 9.1 x 10^-31kg is accelerated between two metal plates with a velocity of 4 x 10⁷ms^-1, the potential difference between the plates is
پاسخ دهید
(A)
4.55 x 10³V
23
A cell of internal resistance 0.01Ω can be measured accurately using the
پاسخ دهید
(C)
potentiometer
24
What optical instrument can best be constructed with converging lenses of focal lengths 50cm and 5cm?
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(D)
Astronomical telescope
25
In a pure semiconductor, the number of electrons in the conduction band is
پاسخ دهید
(B)
equal to the number of holes in the valence band
26
In a thermonuclear reaction, the total initial mass is 5.02 x \(10^{-{2}{7}}\)kg and the total final mass is 5.01 x \(10^{-{2}{7}}\)kg. The energy released in the process is
[c = 3.0 x \(10^8\) ms-1]
پاسخ دهید
(A)
9.0 x 10^-13J
27
A gas would serve as an electrical conductor under
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(A)
reduced pressure and high current
28
An electric generator with a power output of 3.0KW at a voltage of 1.5KV distributes power along cables of resistance 20.0Ω. The power loss in the cables is
پاسخ دهید
(A)
80.0W
29
If the frequency of an emitted x-ray is 1.6 x 10\(^{16}\)Hz, the accelerating potential is?
[e = 1.6 x 10\(^{19}\)C, h = 6.63 x 10\(^{-34}\)Js]
پاسخ دهید
(C)
66.3V
30
If the fraction of the atoms of a radioactive material left after 120years is 1/64, what is the half-life of the material?
پاسخ دهید
(B)
20 years
31
A certain radioactive source emits radiations that were found to be deflected by both magnetic and electric fields. The radiations are
پاسخ دهید
(A)
beta rays
32
A 2H inductor has negligible resistance and is connected to a 50/π Hz A.C. Supply. The reactance of the inductor is
پاسخ دهید
(A)
200 Ω
33
A cell of internal resistance 1Ω supplies current to an external resistor of 3Ω. The efficiency of the cell is
پاسخ دهید
(D)
75%
34
A conductor of length 2m carries a current of 0.8A while kept in a magnetic field of magnetic flux density 0.5T. The maximum force acting on it is
پاسخ دهید
(B)
0.8N
35
Light of energy 5eV falls on a metal of work function 3eV and electrons are liberated. The stopping potential is
پاسخ دهید
(B)
2.0V
36
The velocity y of a particle in a time t is given by the equation
y = 10 + 2t\(^2\)
Find the instantaneous acceleration after 5 seconds
پاسخ دهید
(B)
20 ms^-2
37
A simple pendulum has a period of 17.0s. When the length is shorten by 1.5m, its period is 8.5s. Calculate the original length of the pendulum
پاسخ دهید
(C)
2.0 m
38
A sonometer wire is vibrating at frequency fo. If the tension in the wire is doubled while the length and the mass per unit length are kept constant, the new frequency of vibration is
پاسخ دهید
(D)
f_o√2
39
A travelling wave moving from left to right has an amplitude of 0.15m, a frequency of 550Hz and a wavelength of 0.01m. The equation describing the wave is
پاسخ دهید
(A)
y = 0.15 sin 200π(x - 5.5t)
40
A transverse wave is applied to a string whose mass per unit length is 3 x 10-2kgm-1. If the string is under a tension 12N, the speed of the propagation of the wave is
پاسخ دهید
(B)
20 ms^-1
41
An engineer intends to deviate a light ray from its path by 120^o through reflection from a plane mirror. Calculate the angle of incidence
پاسخ دهید
(C)
30^o
42
The diagram above shows a maximum and minimum thermometer divided into three portions P, Q and R. Which of the following is true about the respective content of P,Q and R
پاسخ دهید
(A)
Alcohol, mercury and alcohol
43
The diagram above shows two capacitors P and Q of capacitance 5μF and 10μF. Find the charges stored in P and Q respectively
پاسخ دهید
(C)
100μC and 200μC
44
In the diagram above a beam of white light travels from a rare to a dense medium. What colours of light do the rays a, b and c respectively represents?
پاسخ دهید
(A)
red, green and blue
45
In the diagram above, the values of V1 and V2 are respectively
پاسخ دهید
(D)
1V and ²/₃V