JAMB Physics 1984 past questions and answers

The distance travelled by a particle starting from rest is plotted against the square of the time elapsed from the commencement of motion. The resulting graph is linear, the slope of this graph is a measure of

1. A.initial displacement
2. B.initial velocity
3. C.acceleration
4. D.half the acceleration
5. E.half the initial velocity

In Fig. 1, PT is a uniform metre rule pivoted at R, the 70 cm mark. Two forces 0.1 N and 0.4 N are applied at Q, the 60 cm mark and S, the 85 cm mark. If the metre rule is kept in equilibrium by the forces and its weight, then the weight of the metre rule is

1. A.0.25 N
2. B.0.30 N
3. C.0.35 N
4. D.0.50 N
5. E.0.56 N

For which of the underlisted quantities is the derived unit ML²T⁻² correct? I. Moment of a force II. Work III. Acceleration

1. A.I only
2. B.II only
3. C.III only
4. D.I and II
5. E.II and III.

What volume of alcohol with a density of 8.4 × 10² kg m⁻³ will have the same mass as 4.2 m³ of petrol whose density is 7.2 × 10² kg m⁻³?

1. A.1.4 m³
2. B.3.6 m³
3. C.4.9 m³
4. D.5.0 m³
5. E.5.8 m³.

For correcting long sight defects in the human eye we require a

1. A.converging lens
2. B.diverging lens
3. C.microscope
4. D.periscope
5. E.plain glass sheet.

For a concave mirror to form a real diminished image, the object must be placed

1. A.behind the mirror
2. B.between the mirror and its focus
3. C.between the focus and the centre of curvature
4. D.at the centre of curvature
5. E.at a distance greater than the radius of curvature.

The unit of quantity of electricity is called

1. A.the ampere
2. B.the volt
3. C.the coulomb
4. D.the ammeter
5. E.electromotive force

The resistance of a wire depends on

1. A.the length of the wire
2. B.the diameter of the wire
3. C.the temperature of the wire
4. D.the resistivity of the wire
5. E.all of the above.

What is the resistance of the circuit shown in Fig. 2

1. A.4 Ω
2. B.11 Ω
3. C.19/5 Ω
4. D.17/4 Ω
5. E.8 Ω

Two cells, each of e.m.f 1.5 V and an internal resistance 2 Ω are connected in parallel. Calculate the current flowing when the cells are connected to a 1 Ω resistor

1. A.0.75 A
2. B.1.5 A
3. C.0.5 A
4. D.1.0 A
5. E.0.6 A

Which of the following components is NOT contained in a dry cell?

1. A.carbon rod
2. B.paste of magnesium dioxide
3. C.paste of ammonium chloride
4. D.zinc case
5. E.copper rod.

Which of the following can be described as high tension transmission?

1. A.High resistance and low voltage
2. B.Low current and high voltage
3. C.High current and low voltage
4. D.High voltage and zero current
5. E.High current and low resistance.

When vibration occurs in an air column, the distance between a node and an antinode is equal to

1. A.one-quarter of the wave length
2. B.one-half of the wave length
3. C.the wave length
4. D.twice the wave length
5. E.four-times the wave length.

Which of the following statements is (are) NOT correct? I. Pressure changes do not affect the speed of sound in air. II. The velocity of sound increases with temperature III. The quality of a note depends only on its frequency.

1. A.I only
2. B.II only
3. C.III only
4. D.I and III
5. E.II and III.

Of two identical tuning forks with natural frequency 256 Hz, one is loaded so that 4 beats per second are heard when they are sounded together. What is the frequency of the loaded tuning fork?

1. A.260 Hz
2. B.252 Hz
3. C.248 Hz
4. D.264 Hz
5. E.258 Hz.

Dewpoint is the temperature at which water vapour

1. A.turns into steam
2. B.solidifies in the atmosphere into ice pellets
3. C.first condenses into liquid form
4. D.is just sufficient to cause cooling
5. E.has a relative humidity of fifty per cent.

The lower and upper fixed points marked on a mercury-in-glass thermometer are 210 mm apart. The end of the mercury column in the tube is 49 mm above the lower fixed point in a room. What is the temperature of the room in degrees Celsius?

1. A.55.3°C
2. B.23.3°C
3. C.49.0°C
4. D.16.1°C
5. E.76.7°C

If a solid changes directly into a gas when heat is applied the process is called

1. A.vaporization
2. B.evaporation
3. C.sublimation
4. D.ionization
5. E.conversion

A plane inclined at an angle of 30° to the horizontal has an efficiency of 60%. The force parallel to the plane required to push a load of 120 N uniformly up the plane is

1. A.60 N
2. B.100 N
3. C.120 N
4. D.200 N
5. E.240 N

A body of mass 5 kg initially at rest is acted upon by two mutually perpendicular forces 12 N and 5 N as shown in Fig. 3. If the particle moves in the direction QA, calculate the magnitude of the acceleration.

1. A.0.40 m s⁻²
2. B.1.40 m s⁻²
3. C.0.26 m s⁻²
4. D.2.60 m s⁻²
5. E.3.40 m s⁻²

A force varying linearly with the distance acts on a body as shown in Fig. 4. The work done on the body by the force during the first 10 metres of motion is

1. A.100 J
2. B.150 J
3. C.200 J
4. D.300 J
5. E.600 J

A simple pendulum, 0.6 m long, has a period of 1.5 s. What is the period of a similar pendulum 0.4 m long in the same location?

1. A.1.5√(2/3) s
2. B.1.5√(3/2) s
3. C.2.25 s
4. D.1.00 s
5. E.2.00 s

A small steel needle is carefully floated on water in a beaker. When a few drops of kerosine are introduced into the water the needle sinks. Which of the following statements correctly explain(s) the observation? I. There is tension on the water surface II. Kerosine reduces the density of water so that the needle becomes denser than water III. Kerosine reduces the surface tension of water.

1. A.I only
2. B.II only
3. C.III only
4. D.I and II
5. E.I and III.

Which of the following statements describes an atom accurately? I. Atoms of all elements are identical II. An atom contains a nucleus and number of electrons III. Due to the electrons in the atom an atom is negatively charged. IV. Electrons in the atom move in circular orbits round the nucleus.

1. A.I and II
2. B.II and III
3. C.III and IV
4. D.II and IV
5. E.I, II and III.

A particle moves in a circular orbit of radius 0.02 m. If the speed of the particle is 0.88 m s⁻¹, calculate its frequency in cycles per second.

1. A.2.0
2. B.7.0
3. C.8.8
4. D.14.0
5. E.17.6

Heat is supplied uniformly at the rate of 100 W to 1.0 × 10⁻² kg of a liquid for 20 seconds. If the temperature of the liquid rises by 5°C, then the specific heat capacity of the liquid is

1. A.2.0 × 10² J kg⁻¹ K⁻¹
2. B.2.0 × 10² J kg⁻¹
3. C.4.0 × 10⁴ J kg⁻¹ K⁻¹
4. D.4.0 × 10⁴ J kg⁻¹
5. E.8.4 × 10³ J kg⁻¹ K⁻¹.

A given mass of an ideal gas occupies a volume V at a temperature T and under a pressure P. If the pressure is increased to 2P and the temperature reduced to ½T, then the percentage change in the volume of the gas is

1. A.0%
2. B.25%
3. C.75%
4. D.300%
5. E.400%

Which of the following properties of matter CANNOT be utilized for temperature measurement? The

1. A.length of a liquid column
2. B.volume of a gas at constant pressure
3. C.pressure of a gas at constant volume
4. D.resistance of a metallic wire
5. E.current produced in a photoelectric effect.

Which of the following statements about the compound microscope and astronomical telescope is (are) correct? I. The final image of a compound microscope is located at infinity. II. The final image of the astronomical telescope is always erect. III. The objective lens of a compound microscope has a very short focal length.

1. A.I only
2. B.II only
3. C.III only
4. D.I and III
5. E.II and III.

A coin is placed at the bottom of a cube of glass t cm thick. If the refractive index of the glass is μ, how high does the coin appear to be raised to an observer looking perpendicularly into the glass?

1. A.1/(t − μ)
2. B.t(μ − 1)/μ
3. C.t(1 + 1/μ)
4. D.−
5. E.μt.

The electromotive force obtained from a simple dynamo may be increased by

1. A.increasing the cross-sectional area of the coil
2. B.winding the coil on a soft-iron armature so as to decrease the magnetic flux through the coil
3. C.increasing the speed of rotation
4. D.making the field magnet longer
5. E.using low-resistance copper coils.

In the circuit shown in Fig. 7, calculate the effective capacitance between X and Y.

1. A.¾ μF
2. B.2 10/13 μF
3. C.12 μF
4. D.4 12/13 μF
5. E.13 μF.

A gun of mass 2.0 kg fires a bullet of mass 1.6 × 10⁻² kg due East. If the bullet leaves the nozzle of the gun with a velocity of 150 m s⁻¹, what is the recoil velocity of the gun?

1. A.150 m s⁻¹ due West
2. B.1.2 × 10⁻⁴ m s⁻¹ due West
3. C.1.2 m s⁻¹ due West
4. D.1.2 m s⁻¹ due East
5. E.150 m s⁻¹ due East

Normal atmospheric pressure at sea-level is 10⁵ N m⁻² and the acceleration due to gravity is approximately 10 m s⁻². If the atmosphere has a uniform density of 1 kg m⁻³, its height is

1. A.100 m
2. B.1000 m
3. C.10000 m
4. D.100 000 m
5. E.1000 000 m

Which of the following is a correct explanation of the inertia of a body?

1. A.Ability to overcome the earth's gravity
2. B.Reluctance to stop moving
3. C.Readiness to start moving
4. D.Reluctance to start moving and its readiness to stop moving once it has begun to move
5. E.Reluctance to start moving its reluctance to stop moving once it has begun to move.

If a water pump at Kainji Dam is capable of lifting 1000 kg of water through a vertical height of 10 m in 10 s, the power of the pump is (g = 10 m s⁻²)

1. A.1.0 kW
2. B.10.0 kW
3. C.12.5 kW
4. D.15.0 kW
5. E.20.0 kW

What is the apparent colour of a RED SHIRT when viewed in PURE green light?

1. A.Red
2. B.Green
3. C.Yellow
4. D.Black
5. E.Blue

The spectrum of white light consists of coloured lights arranged in the following order

1. A.blue, red, green, yellow, indigo, violet, orange
2. B.red, orange, yellow, green, blue, indigo, violet
3. C.red, orange, yellow, indigo, green, blue, violet
4. D.indigo, green, blue, violet, yellow, red, orange
5. E.yellow, blue, green violet, orange, indigo, red.

Cathode rays are

1. A.high-energy electromagnetic waves
2. B.protons
3. C.streams of electrons
4. D.neutrons
5. E.radio waves.

A device that converts sound energy into electrical energy is

1. A.the horn of a motor car
2. B.an A.C. generator
3. C.a microphone
4. D.the telephone ear-piece
5. E.a loudspeaker.

Which of the following I. β-particles II. protons III. neutrons IV. α-particles. may be found in light nuclei?

1. A.I and II
2. B.I and III
3. C.II and IV
4. D.II and III
5. E.I, II and III.

Radio waves have a velocity of 3 × 10⁸ m s⁻¹. A radio station sends out a broadcast on a frequency of 800 kHz. The wavelength of the broadcast is

1. A.375.0 m
2. B.267.0 m
3. C.240.0 m
4. D.37.5 m
5. E.26.7 m

In the diagram above (Fig. 8), X and Y are resistance 4 Ω and 6 Ω respectively. If power dissipation in X is 10 W, then power dissipation in Y is

1. A.2.4 W
2. B.4.0 W
3. C.6.0 W
4. D.6.7 W
5. E.15.0 W

What is the cost of running five 50 W lamps and four 100 W lamps for 10 hours if electrical energy costs 2 kobo per kWh?

1. A.N0.65
2. B.N0.13
3. C.N3.90
4. D.N39.00
5. E.N234.00.

Which of the following statements is (are) NOT true about the emission of photoelectrons from metallic surfaces? I. All metallic surfaces emit the same number of photoelectrons in a given light II. Most metallic surfaces emit the same number of photoelectrons in visible and infrared light. III. A metallic surface emits photoelectrons only if the frequency of the incident light is higher than its own characteristic threshold frequency

1. A.I only
2. B.II only
3. C.I and II
4. D.II and III
5. E.III only

A galvanometer of resistance 5.0 Ω has full-scale deflection for a current of 100 mA. How would its range be extended to 1.0 A? By placing a resistance of

1. A.5/9 Ω in parallel
2. B.9/5 Ω in series
3. C.45 Ω in parallel
4. D.45 Ω in series
5. E.9/5 Ω in parallel

Fig. 9 above represents an insulated cylindrical coil of copper wire wound round a paper tube. The ends of the coil are connected to a sensitive galvanometer. When a magnet was plunged into the coil it was observed that the galvanometer needle gave a deflection. Which of the following correctly describes this experiment?

1. A.The effect illustrated is induced electromotive force
2. B.The strength of the current produced is inversely proportional to the speed with which the magnet is plunged into the coil.
3. C.The direction of the current is always such as to enhance the change producing it
4. D.The galvanometer gave a permanent deflection
5. E.On removing the magnet from the coil the galvanometer deflected in the same direction.