JAMB Physics 1980 past questions and answers

Which of the following statements is true of the law of universal gravitation?

1. A.Any two bodies attract each other with a force which is proportional to the difference of their masses.
2. B.Any two bodies attract each other with a force which is inversely proportional to the square of the distance between them
3. C.Any two bodies attract each other with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them
4. D.Any two bodies attract each other with a force which is directly proportional to the square of the distance between them
5. E.Any two bodies attract each other with a force which is proportional to the sum of their masses.

Which of the following is true of an electrical charge?

1. A.Positive charge means deficit electrons
2. B.Negative charge means excess of electrons
3. C.Electric current means movement of electrons
4. D.All of the above
5. E.A and B only.

Which of the following statements are true in the structure of atoms?

1. A.The atoms of the different elements differ only in the number of protons and electrons
2. B.The number of protons equals the number of electrons
3. C.Atoms are constructed according to the plan of our solar system
4. D.All of the above
5. E.A and C only.

A magnet is similar to a bipolar charged system in that

1. A.it consists of two opposite poles – the north and south poles
2. B.the earth's magnetic field has a south pole near the geographic north pole and a north pole near the geographic south pole
3. C.the force of attraction and repulsion between opposite and between like poles obeys a law identical in form to Coulomb's law for electrostatic charges
4. D.A and B only
5. E.A and C only

In the study of Physics, temperature and heat are often confused with each other. Which of the following statements correctly defines these two elements?

1. A.Temperature is a measure of the average kinetic energy of the molecules of a substance
2. B.Heat is a measure of the total kinetic energy of the molecules in a system
3. C.Different materials require different amounts of heat to cause a given change in temperature
4. D.all of the above
5. E.A and B only.

What is the total resistance in the above diagram?

1. A.5 ohms
2. B.15 ohms
3. C.25 ohms
4. D.35 ohms
5. E.45 ohms.

The total capacitance of the circuit above is

1. A.0.25 mF
2. B.0.50 mF
3. C.0.75 mF
4. D.1.25 mF
5. E.1.50 mF

A given quantity of heat increases the temperature of 150 grams of water from 9°C to 15°C and increases the temperature of an equal volume of oil weighing 100 grams from 9°C to 25°C. The ratio of the specific heat of oil to that of water is

1. A.0.36
2. B.0.46
3. C.0.56
4. D.0.76
5. E.0.86

Which of the following physical quantities is NOT a vector?

1. A.Velocity
2. B.Work
3. C.Force
4. D.Electric field intensity
5. E.Magnetic induction

The motion of the moving skin of a talking drum can rightly be described as

1. A.translational
2. B.random
3. C.rotational
4. D.oscillatory
5. E.transitory

Which of the following does NOT cause a reduction of the surface tension of water?

1. A.Soap solution
2. B.Detergent
3. C.Alcohol
4. D.Camphor
5. E.Grease

The diagram in the above figure shows the prism arrangement in a

1. A.microscope
2. B.stereoscope
3. C.projector
4. D.periscope
5. E.gyroscope

The water at the bottom of a waterfall is slightly warmer than that at the top because part of the

1. A.potential energy raises the water temperature
2. B.water absorbs latent heat from the atmosphere
3. C.kinetic energy is changed into internal energy
4. D.dropping mass of water increases the heat capacity
5. E.A and C above.

A pressure cooker saves both time and fuel in cooking because inside the cooker, the

1. A.boiling point of water is raised
2. B.pressure is constant
3. C.heat is completely trapped
4. D.temperature is evenly distributed
5. E.volume of steam varies.

Which of the following statements is NOT true of the image in a plane mirror? The image is

1. A.the same size as the object
2. B.laterally inverted
3. C.virtual
4. D.magnified
5. E.the same distance behind the mirror as the object is in front.

Any line or section through an advancing wave in which all the particles are in the same phase is called the

1. A.wave length
2. B.wave crest
3. C.wave trough
4. D.wave amplitude
5. E.wave front.

The name given to the characteristic behaviour of substances which set their length perpendicular to a strong magnetic field instead of in line with it is

1. A.magnetization
2. B.paramagnetism
3. C.diamagnetism
4. D.demagnetization
5. E.ferromagnetism.

Which of the following statements on the use of X-rays is incorrect? X-rays are used

1. A.in hospitals to obtain photographs of tissues and bones in the body
2. B.for the treatment of malignant growths like cancer cells
3. C.in detecting fingerprints
4. D.to reveal hidden flaws in metal castings and welded joints
5. E.to detect alterations which have been made to works of art.

What is the relative permitivity of a capacitor if its capacitance with a medium as dielectric is 16 farads and its capacitance with vacuum as dielectric is 2 farads?

1. A.−
2. B.½
3. C.2
4. D.8
5. E.32

If the magnification of a virtual image formed of an object 10 cm from a convex lens is 3, then the focal length of the lens is

1. A.10 cm
2. B.15 cm
3. C.16 cm
4. D.19 cm
5. E.20 cm

What is the acceleration of a particle whose motion is graphically displayed in the above figure?

1. A.0.67 m s⁻²
2. B.0.83 m s⁻²
3. C.0.87 m s⁻²
4. D.92 m s⁻²
5. E.2.0 m s⁻²

Given that SQ = 10 cm and SP = 6 cm, the refractive index of the block of glass shown in the above figure is

1. A.0.30
2. B.0.60
3. C.1.67
4. D.2.33
5. E.2.36

A stand-by generator is connected to fifteen 40 W lamps and a musician's 600 W amplifying system. How much energy is used if the generator runs for 6 hours?

1. A.3.84 kWh
2. B.7.20 kWh
3. C.8.40 kWh
4. D.12.00 kWh
5. E.14.56 kWh.

A tugboat is travelling from Asaba to Onitsha across the River Niger with a resultant velocity of 20 knots. If the river flows at 12 knots, the direction of motion of the boat relative to the direction of water flow is

1. A.36.87°
2. B.53.13°
3. C.90°
4. D.136.87°
5. E.143.13°.

A milliammeter of resistance 5 Ω and full scale deflection of 50 mA is to be used to measure a potential difference of 50 V. The resistance of the multiplier should be

1. A.95 Ω
2. B.110 Ω
3. C.595 Ω
4. D.995 Ω
5. E.1005 Ω.

An object of mass m and volume v is totally immersed in a liquid of density ρ. The tension of a string holding it is

1. A.mg
2. B.(m + ρv)g
3. C.(m − ρv)g
4. D.ρvg
5. E.[m/(m − ρv)]g.

The relative densities of zinc, brass, copper, gold and silver are respectively 7.1, 8.5, 8.9, 19.3, 10.5. A metal ornament which weighs 0.425 kg and can displace 50 × 10⁻⁶ m³ of water is made of

1. A.zinc
2. B.brass
3. C.copper
4. D.gold
5. E.silver.

In the above diagram MN is perpendicular to ON and MP. What is the difference between the moment about N of the force of 20 newtons applied along MP and its moment about O?

1. A.Zero
2. B.0.2 N m
3. C.0.4 N m
4. D.0.8 N m
5. E.0.6 N m

Heat is supplied to a block of ice at 0° until half of it has melted. Which of the following statement is true?

1. A.The temperature rises and the ice expands
2. B.The temperature remains constant and the volume of ice decreases
3. C.The ice gives out heat as it melts
4. D.The mass remains constant and the temperature increases
5. E.The mass decreases because some heat is lost to the atmosphere.

If the volume of a fixed mass of a gas is kept constant, the pressure of the gas

1. A.is inversely proportional to its centigrade temperature
2. B.is inversely proportional to its absolute temperature
3. C.is directly proportional to its centigrade temperature
4. D.is directly proportional to its absolute temperature
5. E.remains constant also.

Which of the following statements about sound is NOT true?

1. A.Sound is a longitudinal wave
2. B.Sound can be reflected and refracted like light
3. C.Sound travels through a vacuum
4. D.Sound moves faster in a steel wire than in air
5. E.Sound can only be produced by vibrating objects.

In the above diagram, a ray of light passes from glass into air. If the angle of incidence in glass is α and the angle of refraction in air is β, which of the following statements is true?

1. A.α = β
2. B.The refractive index of glass is sin θ/sin α
3. C.The ray suffers total internal reflection if β is greater than the critical angle
4. D.The ray will suffer total internal reflection if α is less than the critical angle
5. E.The refractive index of glass is sin α/sin β

In a compound microscope

1. A.there is only one lens
2. B.the objective lens has a shorter focal length than the eyepiece which is convex
3. C.the objective lens has a longer focal length than the eyepiece which is convex
4. D.the objective lens has a shorter focal length than the eyepiece which is concave
5. E.the objective and the eyepiece are both convex and have the same focal lengths.

In sunlight, a blue flower looks blue because we see the flower by the light it

1. A.receives from our eye
2. B.disperses
3. C.absorbs
4. D.refracts
5. E.reflects

In the above diagram a straight vertical wire is placed between two opposite magnetic poles which are separated horizontally by a short distance. If a current is passed down the wire, in which direction will the wire move?

1. A.Towards the observer
2. B.Away from the observer
3. C.Toward the North pole
4. D.Towards the South pole
5. E.Upwards

High Tension (H.T.) transmission means

1. A.to transmit a given amount of power, the tension in the conducting wire must be high
2. B.heat is not lost when current is passed through a conductor
3. C.heat is gained when a given power is transmitted
4. D.a big transformer is required to transmit power
5. E.transmission of power at low current and high voltage.

The best material for the core of the primary and secondary coils of an induction coil is

1. A.copper, because it is a good conductor of electricity
2. B.steel, because it becomes magnetic and retains its magnetism for a long time
3. C.rubber, because it is a good insulator and the user is prevented from shock
4. D.soft iron, because it becomes magnetic but easily loses its magnetism
5. E.glass, because it is transparent.

Which of the following radiations cannot be deflected by a magnetic field?

1. A.α
2. B.β
3. C.γ
4. D.β and γ
5. E.None of them

Which of the following elements is the best absorber of X-rays?

1. A.Hydrogen
2. B.Oxygen
3. C.Calcium
4. D.Copper
5. E.Lead

A calorimeter of thermal capacity 80 J contains 20 g of water at 25°C. Water at 100°C is added so that the final temperature of the set-up is 50°C. The amount of water added is (Heat capacity of water = 4.18 J/g/°C)

1. A.20 g
2. B.25 g
3. C.45 g
4. D.50 g
5. E.100 g.

A man stands one-third of the way between two walls and claps his hands. He hears two distinct echoes 1 s apart. If the speed of sound is 330 m s⁻¹ the distance between the walls is

1. A.33 m
2. B.110 m
3. C.220 m
4. D.330 m
5. E.495 m

A cell has an open circuit voltage V₁ and a closed circuit voltage V₂ when a current I is flowing through it. Therefore, the internal resistance of the cell is

1. A.V₂/I
2. B.V₁/I
3. C.(V₁ + V₂)/I
4. D.(V₁ − V₂)/I
5. E.(V₂ − V₁)/I.

According to Ohm's law, the ratio V/I is constant for

1. A.an electrolyte
2. B.a diode
3. C.a transistor
4. D.silver
5. E.all of the above

The activity of a radioactive substance depends on

1. A.temperature and purity
2. B.temperature and age
3. C.purity and age
4. D.age, purity and temperature
5. E.none of the above.

Natural radioactivity consists of the emission of

1. A.α-particles and β-rays
2. B.α-particles and X-rays
3. C.γ-rays and X-rays
4. D.α-particles, β-rays and γ-rays
5. E.α-particles, β-rays, γ-rays and X-rays.