JAMB Physics 1982 past questions and answers

A man stands on a spring scale placed in a lift. The lift descends at constant velocity. As a result, the scale reads a weight

1. A.greater than the weight of the man
2. B.the same as the weight of the man
3. C.of zero
4. D.less than the weight of the man
5. E.greater than the weight of the man by 1 kg.

One of the following readings represents the measurement of the length of a metal rod using vernier callipers. Taking the reading accuracy into consideration, the most likely one is

1. A.5.16 cm
2. B.5.165 cm
3. C.5.0 cm
4. D.5.160 cm
5. E.5 cm

When equal weights of iron and water are subjected to an equal supply of heat, it is found that the piece of iron becomes much hotter than water after a shorter time because

1. A.the specific heat of iron is higher than that of water
2. B.iron is in solid form
3. C.water is in liquid form
4. D.the specific heat of water is higher than that of iron
5. E.the specific heat of iron is infinite

The tyre pressure of a car was found to be 150 cm Hg in the morning at a temperature of 27°C. Hard driving in the afternoon raised the temperature of the tyres to 57°C. The tyre pressure had by the afternoon

1. A.increased by 15.0 cm Hg
2. B.decreased by 15.0 cm Hg
3. C.increased by 22.50 cm Hg
4. D.decreased by 22.50 cm Hg
5. E.remained constant.

The echo of a sounder from the bottom of an ocean is heard 2.5 seconds later. If the speed of sound in water is 1,400 m s⁻¹, the depth of the ocean is

1. A.1,750 m
2. B.3,500 m
3. C.1,400 m
4. D.2,800 m
5. E.2,100 m

In order to produce a parallel beam of light, a lamp is placed at a distance from the concave mirror equal to

1. A.the radius of curvature
2. B.half the radius of curvature
3. C.half the focal length
4. D.twice the focal length
5. E.twice the radius of curvature.

The speed of light in air is 3.00 × 10⁸ m s⁻¹. Its speed in glass having a refractive index of 1.65 is

1. A.1.65 × 10⁸ m s⁻¹
2. B.3.00 × 10⁸ m s⁻¹
3. C.4.95 × 10⁸ m s⁻¹
4. D.1.82 × 10⁸ m s⁻¹
5. E.6.00 × 10⁸ m s⁻¹.

Which of the circuits illustrated below will give a total resistance of 1 Ω?

1. A.A
2. B.B
3. C.C
4. D.D
5. E.E

An electric iron is rated at 1000 watts, 250 V. The corresponding maximum resistance and accompanying current is

1. A.62.5 A 4.0 Ω
2. B.16.0 A 62.5 Ω
3. C.62.5 A 16.0 Ω
4. D.4.0 A 62.5 Ω
5. E.4.0 A 250 Ω.

The force responsible for holding the moon in its orbit around the earth against the gravitational pull of the earth is

1. A.centrifugal
2. B.rotational
3. C.reaction
4. D.centripetal
5. E.tractional.

Two taxis leave Benin and Agbor some 80 km apart at 1200 hr (Fig. 1). From the distance time graph shown, the distance of their meeting point P, from Benin, and the time of their meeting are

1. A.27 km, 1218 hr
2. B.29 km, 1315 hr
3. C.40 km, 1418 hr
4. D.53 km, 1436 hr
5. E.60 km, 1500 hr

A mango fruit drops from a branch 10 m above the ground. Just before hiting the ground its velocity is (g = 10 m s⁻²).

1. A.10√2 m s⁻¹
2. B.10/√2 m s⁻¹
3. C.100 m s⁻¹
4. D.5√2 m s⁻¹
5. E.200 m s⁻¹.

Which of the following machines does NOT apply the lever principle?

1. A.Claw hammer
2. B.Wheel barrow
3. C.Single moving pulley
4. D.Sugar tongs
5. E.Nutcrackers

The accurate measurement of the relative density of substances in powder or granular form can be done using a beam balance and a

1. A.pipette
2. B.burette
3. C.measuring cylinder
4. D.density bottle
5. E.eureka can

Which of the following statements is NOT true? Thermostats are used to control the temperature of

1. A.pressure cookers
2. B.laundry irons
3. C.hot water storage tanks
4. D.aquaria for tropical fish
5. E.heated apartments.

250 g of lead at 170°C is dropped into 100 g of water at 0°C. If the final temperature is 12°C, the specific heat of lead is (specific heat capacity of water is 4,200 J/kg°C)

1. A.39.5 J/kg°C
2. B.50.4 J/kg°C
3. C.127.6 J/kg°C
4. D.154.6 J/kg°C
5. E.173.4 J/kg°C.

An object 15 cm high is 30 cm from a pin-hole camera. If the height of the image formed at the back of the camera is 10 cm, the image distance is

1. A.20 cm
2. B.45 cm
3. C.54 cm
4. D.63 cm
5. E.70 cm

The combination of sound waves with different frequencies is known as

1. A.interference
2. B.diffraction
3. C.superposition
4. D.forced vibrations
5. E.resonance

Why does a piece of cork float on water?

1. A.There is no upthrust on it when completely immersed in water
2. B.The upthrust on it when completely immersed in water is greater than its weight in air
3. C.The upthrust on it when completely immersed in water is less than its weight in air
4. D.Its specific gravity is greater than that of water
5. E.Its specific gravity is the same as that of water.

The water manometer in Fig. 2 is measuring the pressure of the gas supply. If the specific gravity of mercury is 13.6 and the atmospheric pressure is 70 cm of mercury, what is the total pressure of the gas supply in cm of water?

1. A.67 cm
2. B.73 cm
3. C.949 cm
4. D.952 cm
5. E.955 cm

A rod of length 10 cm is heated through 100°C and its final length is 10.26 cm. What is the co-efficient of linear expansion of the rod?

1. A.0.026 per degree centigrade
2. B.0.00026 per degree centigrade
3. C.0.26 per degree centigrade
4. D.1.0026 per degree centigrade
5. E.0.0026 per degree centigrade.

In Fig. 3 an incident ray XY makes an angle of 15° with a fixed line AY which is normal to the surface of a plane mirror. If the mirror is turned as indicated by the arrow, through 40°, what angle will the reflected ray make with AY?

1. A.25°
2. B.40°
3. C.15°
4. D.55°
5. E.95°

If the refractive index of a medium is √2, what is the critical angle?

1. A.45°
2. B.50°12'
3. C.56°25'
4. D.75°
5. E.90°.

The arrow represents an object in front of a convex lens whose focal points are X and Y (Fig. 4). The image formed is

1. A.between X and P
2. B.between P and Y
3. C.between Y and Z
4. D.outside W
5. E.outside Z.

What is the resultant capacity of the circuit (Fig. 5) given above?

1. A.1.5 μF
2. B.18.0 μF
3. C.6.0 μF
4. D.6.8 μF
5. E.8.83 μF

What is the resultant resistance of the circuit (Fig. 6) given above?

1. A.11 Ω
2. B.8 Ω
3. C.4 Ω
4. D.3.6 Ω
5. E.4.3 Ω

A body is acted on by forces applied at points P and Q as shown (Fig. 7). Their resultant is equal to

1. A.2√5 N in a direction N 56°E
2. B.2√5 N in a direction N 56°W
3. C.2√13 N in a direction N 56°E.
4. D.2√13 N in a direction N 56°W
5. E.√10 N in a direction N 56°E.

A uniform beam PQ of mass 20 kg and length 5 m is balanced as shown (Fig. 8). A man of weight 800 N stands at M such that QM = 2 m. The reactions at P and Q respectively are (take g = 10 m s⁻²).

1. A.300 N and 500 N
2. B.420 N and 580 N
3. C.220 N and 380 N
4. D.580 N and 420 N
5. E.380 N and 220 N

The value of the series resistance required to convert the above galvanometer (Fig. 9) into a voltmeter with a full range deflection of 15 V is

1. A.985 ohms
2. B.990 ohms
3. C.995 ohms
4. D.1,000 ohms
5. E.1,005 ohms

As a positively charged rod is brought nearer to the top cap of a positively charged gold leaf electroscope, the divergence of the leaves will

1. A.decrease to zero
2. B.steadily increase
3. C.decrease to zero and then increase
4. D.remain constant
5. E.increase to a maximum and then decrease.

Which of the following statements is NOT true of γ-rays?

1. A.γ-rays belong to the electromagnetic spectrum
2. B.γ-rays do not carry an electron charge
3. C.γ-rays obey the inverse cube law in air
4. D.The thickness of aluminium which stops β-particles has a negligible effect on γ-radiation.
5. E.The difference between γ-rays and X-rays is that γ-rays originate from energy changes in the nuclei of atoms, while X-rays come from energy changes associated with the electron structure of atoms.

A rocket burns 0.01 kg of fuel each second and ejects it as a gas with a velocity of 5,000 m/s. What force does the gas exert on the rocket?

1. A.500,000 N
2. B.500 N
3. C.50 N
4. D.5,000 N
5. E.50,000 N

Which of the following statements is true of a body which is moving in a straight line with uniform acceleration? The velocity of the body

1. A.is also uniform
2. B.must always be zero when the body stops accelerating
3. C.will increase with time in the direction of the acceleration
4. D.is equal to the quotient of distance travelled and time
5. E.is the product of the distance travelled and time.

Two mirrors of the same length are arranged as shown in the diagram (Fig. 10). A ray of light NO strikes the system at O and emerges along PQ. The emergent ray has been deviated through

1. A.220°
2. B.200°
3. C.210°
4. D.180°
5. E.230°

A heater marked 50 W will evaporate 0.005 kg of boiling water in 50 seconds. The specific latent heat of vaporization of water in J/kg is

1. A.5.0 × 10⁶
2. B.1.0 × 10⁶
3. C.2.5 × 10⁶
4. D.2.5 × 10⁵
5. E.5.0 × 10⁵

A high-resistance voltmeter reads 3.0 V when connected across the terminals of a battery on open circuit and 2.6 V when the battery supplies a current of 0.2 A through a lamp. The resistance of lamp is

1. A.2.00 Ω
2. B.13.00 Ω
3. C.0.52 Ω
4. D.0.13 Ω
5. E.1.50 Ω

A magnetic needle is suspended first at the earth's north magnetic pole and then at a point on the magnetic equator. The respective angles between the needle and the horizontal are

1. A.0° and 0°
2. B.60° and 60°
3. C.90° and 90°
4. D.90° and 0°
5. E.0° and 90°.

The equation P^x V^y T^z = constant

1. A.x = 0, y = 0, z = 1
2. B.x = 1, y = 0, z = 0
3. C.x = 1, y = 1, z = 0
4. D.x = 1, y = 1, z = 1
5. E.x = 1, y = 1, z = −1.

The area under a force-distance graph represents

1. A.acceleration
2. B.velocity
3. C.power
4. D.work
5. E.momentum

The range of accommodation of a normal human eye is

1. A.0 m to 0.1 m
2. B.0 m to 0.25 m
3. C.0.10 m to 0.25 m
4. D.0.10 m to infinity
5. E.0.25 m to infinity.

A hydrometer is an instrument for measuring the

1. A.depth of water in a vessel
2. B.relative density of a liquid by the method of flotation
3. C.relative density of a liquid by finding the apparent loss in weight
4. D.relative humidity of the air
5. E.atmospheric pressure when the air is humid.

In the given diagram (Fig. 11), the values of the vertically suspended weight W and the angle X are

1. A.2 kgf, 30.9°
2. B.4 kgf, 36.9°
3. C.6 kgf, 53.1°
4. D.8 kgf, 73.8°
5. E.12 kgf, 106.2°

In a resonance tube experiment (Fig. 12) the frequency of the tuning fork is 750 Hz and the resonating length of the air column is 0.3 m as shown. The velocity of the wave is

1. A.1,850 m s⁻¹
2. B.225 m s⁻¹
3. C.300 m s⁻¹
4. D.53 × 10⁻⁵ m s⁻¹
5. E.2,500 m s⁻¹

The point beyond which a stretched spring does not return to its original length is called the

1. A.breaking point
2. B.elastic limit
3. C.spring constant
4. D.elasticity point
5. E.release point.

A 10 g mass placed on the pan of a spring balance causes an extension of 5 cm. If a 15 g mass is placed on the pan of the same spring balance the extension is

1. A.3.3 cm
2. B.6.5 cm
3. C.7.5 cm
4. D.10.8 cm
5. E.15.0 cm