JAMB UTME - Physics - 1988

A cell of internal resistance 2 ohms supplies current to a 6 ohms resistor. The efficiency of the cell is

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Efficiency = $\frac{IR}{I(R+r)}$ x 100

= $\frac{6}{I(2+6)}$ x 100

= 75%

Which of the following media allow the transmission of sound wave through them i. Air. ii. Liquids. iii. Solids.

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The figure above shows three different ways of hanging a heavy picture from a hook. the tension in the string will be

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A note is called an octave of another note when

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Two forces whose resultant is 100N, are at right angle to each other. If one of them makes an angle 30o with the resultant, determine its magnitude.

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COS 30o = $\frac{F_1}{100}$

F1 = 86.6N

Which of the following properties is/are common to all waves? i. Diffraction ii. Refraction iii. Interference

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A slight loading of a tuning fork has the effect of

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The amount of heat needed to raise the temperature of 10kg of copper by 1k is its

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An object is placed 10cm in front of a concave mirror of focal length 15cm. What is the position and nature of the image formed?

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F = $\frac{uv}{u+v}$

15 = $\frac{10\times v}{10+v}$

v = -30cm

A force, 10N, drags a mass 10kg on a horizontal table with an acceleration of 0.2ms. If the acceleration due to gravity is 10ms-1, the coefficient of friction between the moving mass and the table is

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$\mu$mg = ma

$\mu$ x 10 x 10 = 10 x 0.2

$\mu$ = 0.02

In a certain fusion reaction, a deuteron (${}_1^{2}H$) interacts with a triton (${}_1^{3}He$) and produces an a-particle (${}_2^{4}He$) and a second product. The second product is

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${}_1^{2}H$ + ${}_1^{3}H$ $\to$ ${}_2^{4}He$ + ${}_0^{1}He$

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$\frac{\text{speed of driver}}{\text{speeder driven}}$ = $\frac{\text{no. of teeth of driver}}{\text{no. of teeth of driven}}$

$\frac{120}{V}$ = $\frac{20}{60}$

v = 360 rev s-1

Which of the following are the correct SI units of the quantities indicated? i.N(Force) II. Mn-1 (Torque) iii. watt(Power) iv. kgms-2

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A spectrum of sunlight is said to be impure when

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In the circuit diagram above, the ammeter reads a current of 3A when R is 5 ohms and 6A when R is 6 ohms,the value of the unknown resistance X is

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A tap supplies water at 25oC while another supplies water at 75oC. If a man wishes to bathe with water at 40oC, the ratio of the mass of cold water to the mass of hot water required is

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Heat lost = heat gained

mh x c x (75 - 40) = mc x c x (40 - 25)

$\frac{m_h}{m_c}$ = $\frac{35}{15}$

= $\frac{7}{3}$

Which of the following symbolic representations is correct for an atom X with 22 electrons and 43 neutrons?

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When white light is dispersed by a spectrometer, the component having the shortest wavelength is

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When heat is applied to one end of a metal rod, the molecules at the other end soon begin to vibrate with greater amplitude than before because heat has been transferred by

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The figure above shows two waveforms X and Y. If the frequency of X is 30Hz what is the frequency of Y

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A piano wire 0.5m long has a total mass of 0.01kg and is stretched with a tension of 800N. Calculate the frequency of the wire when it sounds its fundamental note

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F = $\frac{1}{2L}$$\sqrt{\frac{T}{m}}$

N:B m is mass per length

= $\frac{0.01}{0.5}$

= 0.02kgm-1

F = $\frac{1}{2\times 0.5}$$\sqrt{\frac{800}{0.02}}$

= 200Hz

A particle starts from rest and moves with a constant acceleration of 0.5ms-2. The distance covered by the particle in 10s is

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X = ut + $\frac{1}{2}$at

= (0 x 10) + ($\frac{1}{2}$ x 0.05 x 10 x 10)

= 25m

A lorry travels 10km northwards, 4km eastwards, 6km southwards, 4km westwards to arrive at a point T. What is the total displacement?

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When one arm of a U-tube manometer is connected to a gas supply, the levels of mercury in the two arms of the U-tube is shown in the figure above, if the atmospheric pressure is 76.0cm hg, the gas pressure is

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A body whose mass is 2kg and has a volume of 500cm just floats when completely immersed in a liquid. Calculate the density of the liquid

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since the object floats, density of liquid = density of object

D = $\frac{m}{v}$

= $\frac{2}{500\times 10}$

= 4.0 x 103kgm-3

How long will it take a 60kg man to climb a height of 22m if he expended energy at a rate of 0.25kW. [g = ms-2]

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power = mgh

0.25 x 103 = $\frac{60\times 10\times 22}{t}$

t = 52.8 sec

The product PV where P is pressure and V is volume has the same unit as

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PV = $\frac{N}{m^2}$ x $\frac{m^2}{1}$

= Nm

A particle is injected perpendicularly into an electric field, it travels along a curved path as depicted in the image above,the particle is

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The wire X in the figure above is at right angles to the plane of the paper and carries a current into the paper. at which of the points labelled 1-4, will the magnetic flux density due to this current be in the same direction as that of the horizontal component of earth's magnetic field

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Which of the following statement is TRUE of ultraviolet, visible and infra-red rays?

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Which of the following factors affects the speed of sound in air? i. Temperature ii. pressure iii. Frequency

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Which of the following quantities are scalars? i. Electrical potential ii. Torque iii. Momentum iv. Kinetic energy

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Two strings of the same length and under the same tension gives notes of frequencies in the ratio 4 : 1. The masses of the strings are in the corresponding

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F = $\frac{1}{2L}$$\sqrt{\frac{T}{m}}$

$\frac{F_1}{F_2}$ = $\sqrt{\frac{m_2}{m_1}}$

$\frac{1}{4}$ = $\sqrt{\frac{m_2}{m_1}}$

$\sqrt{\frac{m_2}{m_1}}$ = $\frac{1}{2}$

When a resistance R is across a cell, the voltage across the terminals of the cell is reduced to two-third of its normal value. The internal resistance of the cell is

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IR = $\frac{2}{3}$ I(R + r)

r = $\frac{1}{2}$R

In the figure above, what is the angle of reflection of the ray of light at mirror M?

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E, F and G are yellow, red and cyan transparent light filters respectively. The color of a white opaque object when viewed through the arrangement of the filters above is

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When taking a penalty kick, a footballer applies a force of 30.0N for a period of 0.05s. if the mass of the ball is 0.075kg, calculate the speed with which the ball moves off.

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F = $\frac{m(v-u)}{T}$

30 = $\frac{0.75(v-0)}{0.05}$

v = 20ms-1

A household refrigerator is rated 200 watts. If electricity costs 5k per kWh, what is the cost of operating it in 20 days?

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Energy(kWhr) = 200 x 10-3 x 20 x 24

= 96kwhr

1 kwhr cost 5 kobo ; 96 kwhr will cost

5 x 96 = 480 kobo

The speed of sound in air at sea-level is 340ms-1 while that of light is 300 000kms-1. How far (to the nearest meter) from the center of a thunderstorm is an observer who hears a thunder 2s after a lightening flash?

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Distance = 340 x 2 = 680ms-1

The figure above shows displacement-time graphs for three different motions. which of the following statements is correct

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Which of the following phenomena explains the formation of a mirage? i. Reflection ii. Refraction iii. Diffraction

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A dynamo primarily combines

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Which of the following ammeters may be used to measure alternating currents? i. moving-coil ammeter ii. moving-iron ammeter iii. hot-wire ammeter

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To obtain a magnification of 2.5, how far should an object be placed from the pole of a thin converging lens of focal length 10.20m?

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v = 2.5u

F = $\frac{uv}{u+v}$

0.2 = $\frac{u\times 2.5u}{u+2.5u}$

u = 0.28m

The principle of operation of an induction coil is based on

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