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JAMB UTME - Physics - 1983

Question 1 Report

which of the following is NOT correct? i. the pitch of a sound note depends on the frequency of vibrations. ii. the intensity of a sound note is proportional to the amplitude of vibrations. iii. beats are produced by two sources of sound because one wave is travelling faster than the other. iv. when two sources of sound of frequencies 500Hz and 502Hz are sounded together, a beat frequency of 2Hz is observed. v. the first harmonic of a tone have double the frequency of the fundamental note.

i and ii

ii and iii

i and iii

iii and iv

iv and v

Current Electricity

Sound Waves

Reflection Of Light At Plane And Curved Surfaces

Magnets And Magnetic Fields

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Question 5 Report

If the pressure on 100cm3 of an ideal gas is doubled while its kelvin temperature is halved, then the new volume of the gas will become

25cm3

50cm3

100cm3

200cm3

400cm3

Answer Details

$\frac{P_{1} V_{1}}{T_{1}}$ = $\frac{P_{2} V_{2}}{T_{2}}$

P2 = 2P ; T1 = 2T2

therefore, $\frac{P_{1} \times 1000}{2 T_{2}}$ = $\frac{2 P_{2} \times V_{2}}{T_{2}}$

= 25cm

Read lesson note on Pressure (JAMB)

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Question 6 Report

a force of 16N applied 4.0kg block that is at rest on a smooth, horizontal surface. What is the velocity of the block at t = 5 seconds?

4ms-1

10ms-1

20ms-1

50ms-1

80ms-1

Answer Details

F = ma

= $\frac{m (u - v)}{t}$

16 = $\frac{4 (v - 0)}{5}$

v = 20ms-1

Read lesson note on Newton’s Laws Of Motion (WAEC)

Newton’s Laws Of Motion

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Question 9 Report

A man of mass 50kg ascends a flight of stairs 5m high in 5 seconds. If acceleration due to gravity is 10ms-2, the power expended is

100W

200W

250W

400W

500W

Answer Details

Power = $\frac{force x distance}{time}$

= 50 x 10 x 5 = 500W

Read lesson note on Gravitational Field (JAMB)

Gravitational Field

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Question 10 Report

1,000 identical drops of oil of density 500kgm-3 have a total mass of 5 x 10-4kg. One of the drops forms a thin film of area 0.5m2 on water. The thickness of the film is

2 x 10-8m

2 x 10-9m

2 x 10-7m

3 x 10-9m

2.8 x 10-8m

Answer Details

Mass of one oil = $\frac{5 \times 10^{- 4}}{1000}$

= 5 x 10-4kg

Density = $\frac{mass}{area x thickness}$

500 = $\frac{5 \times 10^{- 7}}{0.5 x thickness}$

thickness = 2 x 10-9m

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Question 14 Report

The speed of light in vacuum is 3.0 x 108ms-1. If the refractive index of a transparent liquid is $\frac{4}{3}$ , then the speed of light in the liquid is

0.44 x 10 8ms-1

2.25 x 10 8ms-1

3.0 x 10 8ms-1

4.0 x 10 8ms-1

4.33 x 10 8ms-1

Answer Details

n = $\frac{speed in air}{speed in water}$

$\frac{4}{3}$ = $\frac{3 \times 10^{8}}{v}$

v = 2.25 x 10 8ms-1

Read lesson note on Motion (JAMB)

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Question 16 Report

The total length of a spring when a mass of 20g is hung from its end is 14cm, while its total length is 16cm when a mass of 30g is hung from the same end. Calculate the unstretched length of the spring assuming Hooke's law is obeyed.

9.33cm

10.00cm

10.66cm

12.00cm

15.00cm

Answer Details

Let unstretched length = L

e1 = 14 - L and e2 = 16 - L

Using, $\frac{m_{1}}{e_{1}}$ = $\frac{m_{2}}{e_{2}}$

$\frac{20}{14 - L}$ = $\frac{30}{16 - L}$

L = 10cm

Read lesson note on Elasticity (JAMB)

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Question 25 Report

A machine has a velocity ratio of 5. It requires a 50kg weight to overcome a 200kg weight. The efficiency is

4%

5%

40%

50%

80%

Answer Details

Efficiency = M.A x 100%

= $\frac{200}{50}$ x $\frac{1}{5}$ x 100

= 80%

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Question 27 Report

In a resonance tube experiment, a tube fixed length is closed at one end and several tuning forks of increasing frequency used to obtain resonance at the open end. If the tuning fork with the lowest frequency which gave resonance had a frequency f1 and the next tuning fork to give resonance had a frequency f2, find the ratio $\frac{f^{2}}{f^{2}}$ .

8

3

2

1

2

1

3

Answer Details

λ_{1}

= 4L1 and

λ_{2}

= -L1

F $λ$ = velocity

F1 x $λ_{1}$ = F2 x
$λ_{2}$ ; F1 x 4 $λ_{1}$ = F2 x - $λ_{2}$

= $\frac{F_{2}}{F_{1}}$ = 3

Read lesson note on Newton’s Laws Of Motion (WAEC)

Read lesson note on Motion (JAMB)

Read lesson note on Work, Energy And Power (WAEC)

Newton’s Laws Of Motion

Work, Energy And Power

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Question 29 Report

A ship travelling towards a cliff receives the echo of its whistle after 3.5 seconds. A short while later, it receives the echo after 2.5 seconds. If the speed of sound in air under the prevalling condition is 250ms -1, how much closer is the ship to the cliff?

10m

125m

175m

350m

1,000m

Answer Details

Difference in time = 1 sec.

echo time = 1 $\div$ 2 = 0.5 sec.

= 0.5 x 250

= 125m

Read lesson note on Properties Of Waves: Reflection, Refraction, Diffraction (WAEC)

Properties Of Waves: Reflection, Refraction, Diffraction

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Question 33 Report

A milliameter with full scale deflection of 10mA has an internal resistance of 5 ohms. It would be converted to an ammeter with a full scale deflection of 1A by connecting a resistance of

\frac{5}{99}

ohms in series with it

\frac{5}{99}

ohms in parallel with it

\frac{99}{5}

ohms in series with it

\frac{99}{5}

ohms in parallel with it

2 ohms in series with it

Answer Details

I = 1 - (10 x 10-3)

= 0.99A

IR = 10 x 10 x 10-3 x 5

R = $\frac{5}{99}$ $Ω$

Read lesson note on Capacitors (JAMB)

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Question 34 Report

If the force of a charge of 0.2 coulomb in an electric field is 4N, then the electric field intensity of the field is

0.8

0.8N/C

20.0N/C

4.2N/C

Answer Details

Field intensity = $\frac{f o r c e}{c h a r g e}$

$\frac{4}{0.2}$ = 20N/C

Read lesson note on Electric Field (WAEC)

Electric Field

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Question 35 Report

PQ is a thin rod on a horizontal table, RS is a plane mirror inclined at $45^{\circ} C$ to the horizontal as shown above. The image of PQ as seen in the mirror by the eye T is

horizontal

parallel to the mirror

at infinity

vertical

highly magnified

Electrostatics

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Question 36 Report

Which of the following best describes the energy changes which take place when a steam engine drives a generator which lights a lamp?

heat

\to

light

\to

sound

\to

kinetic

kinetic

\to

light

\to

heat

\to

electricity

heat

\to

kinetic

\to

electricity

\to

heat

\to

light

electricity

\to

kinetic

\to

heat v light

heat

\to

sound

\to

kninetic v electricity

Current Electricity

Heat Energy

Work, Energy And Power

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Question 37 Report

An electric current of 3Aflowing through an electric heating elements of resistance 20 embedded in 1,000g of an oil raises the temperature of the oil by 10oC in 10 seconds then the specific heat capacity of the oil is

1.8Jg-1oC

0.6Jg-1oC

0.18Jg-1oC

18Jg-1oC

0.06Jg-1oC

Answer Details

Heat energy = Electrical energy

mc $Ω$ = I2RTt

1000 x c x 10 = 3 x 3 x 20 x 10

0.18Jg-1oC

Read lesson note on Heat Energy (WAEC)

Heat Energy

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Question 38 Report

A 24V potential difference is applied across a parallel combination of four 6-ohms resistor, The current in each resistor is

1A

4A

16A

18A

36A

Answer Details

I = $f r a c 246$

= 4A

Read lesson note on Current Electricity (JAMB)

Current Electricity

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Question 39 Report

The linear expansivity of brass is 2 x 10-5oC-1. If the volume of a piece of brass is 10cm3 at 0oC, what will be its volume at 100oC?

10.02cm3

10.04cm3

10.06cm3

10.20cm3

102.00cm3

Answer Details

3 x $α$ = $\frac{V_{2} - V_{1}}{Δ θ \times V_{1}}$

3 x 2 x 10-5 = $\frac{V_{2} - 10}{10 \times 100}$

V2 = 10.06cm3

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 40 Report

The difference of potential between the terminals of cells is 2.2 volts. When a 4ohm resistor is connected across the terminals of this cells, the potential difference is 2 volts. What is the internal resistance of the cell?

0.10 ohms

0.25ohms

0.40ohms

2.50ohms

4.00ohms

Answer Details

IR = 2 and Ir = 0.2

I = $\frac{2}{R}$ ; I = $\frac{0.2}{r}$

$\frac{2}{4}$ = $\frac{0.2}{r}$

r = 0.4 $Ω$

Read lesson note on Current Electricity (JAMB)

Read lesson note on Electrical Energy And Power (JAMB)

Read lesson note on Electric Cells (JAMB)

Current Electricity

Electrical Energy And Power

Electric Cells

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Question 43 Report

The refractive index of liquid is 1.5. If the velocity of light in vacuum is 3.0 x 108ms-1, the velocity of light in the liquid is

1.5 x 108m-1

2.0 x 108m-1

3.0 x 108m-1

4.5 x 108m-1

9.0 x 108m-1

Answer Details

n = $\frac{speed in air}{speed in glass}$

1.5 = $\frac{3 \times 10^{4}}{speed in glass}$

speed in glass = 2 x 108ms-1

Read lesson note on Electromagnetic Waves: Types Of Radiation In Elect (WAEC)

Electromagnetic Waves: Types Of Radiation In Elect

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