JAMB UTME - Physics - 2011 | Green Bridge CBT

Question 1 Report

An object of mass 2 kg moves with a velocity of 10 ms1 round at circle of radius 4 m. Calculate the centripetal force on the object

25 N

100 N

50 N Correct answer

40 N

Answer Details

Centripetal force,
F =

\frac{m v^{2}}{r}

\frac{2 \times 10^{2}}{4}

\frac{200}{4}

= 50N

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Motion

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Question 2 Report

If a tube of small radius opened at both ends is placed in a liquid, the liquid will

remain at the same level irrespective of whether the liquid wet the glass or not

fall below the liquid level if the liquid wets the glass

falls below the liquid level if the liquid does not wet the glass Correct answer

rise above the liquid level if the liquid does not wet the glass

Answer Details

The liquid will rise up the capillary if it wets glass and falls below its wets glass and falls below its initial level if it does not wet glass

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Fluid At Rest

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Question 3 Report

Two resistors 5Ω and 10Ω are arranged first in series and later in parallel to a 24V source, the ratio of total power dissipated in the series and parallel arrangements respectively is

5:3

1:50

50:1

3:5

No Correct Option

Correct answer

Answer Details

Read lesson note on Capacitors (JAMB)

Read lesson note on Simple A.C Circuits (JAMB)

Capacitors

Simple A.C Circuits

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Question 4 Report

A radioactive isotope has a decay constant of 10-5s4. Calculate half life

6.93 x 105s

6.93 x104s Correct answer

6.93 x 104s

Answer Details

T (1)/2 = (0.693)/λ = (0.693)/10-5
= 0.693 x 105
= 6.93 x 104 sec

Read lesson note on Electromagnetic Field (Part 2) (WAEC)

Electromagnetic Field (Part 2)

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Question 5 Report

A perfect emitter or absorber of radiant energy is a

conductor

black body Correct answer

white body

red body

Answer Details

Dull, black surface are good emitters or absorbers of energy

Read lesson note on Electric Field (WAEC)

Read lesson note on Electromagnetic Field (Part 2) (WAEC)

Electric Field

Electromagnetic Field (Part 2)

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Question 6 Report

In the circuit above, three resistors, 2Ω, 4Ω and 12Ω are connected in parallel and a 12V battery is connected across the combination. The current flowing through the 12Ω resistors is

14.4 A

1.0 A Correct answer

3.2 A

9.6 A

Answer Details

I	V
	R

=	12
	12

= 1A

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Question 7 Report

Two balls X and Y weighing 5 g and 50 kg respectively were throne up vertically at the same time with a velocity of 100 ms1 .How will their positions be one second later?

X and Y will be 500 m from each other

Y will be 500 m ahead of X

X will be 500 m ahead of Y

X and Y both be 500 m from the poin of throw Correct answer

Answer Details

v2 = U2 - 2G s
0 = 1002 - 2 x 10 x s = 10000 - 20s
s = (10000)/20 = 500m
Which is independent of mass.the two bodies where acted upon by the same retarding force of gravity which is independent of mass of the body; therefore both will be 500 m from the point of throw.

Read lesson note on Rectilinear Acceleration (WAEC)

Read lesson note on Position, Distance And Displacement (WAEC)

Read lesson note on Motion (WAEC)

Rectilinear Acceleration

Position, Distance And Displacement

Motion

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Question 8 Report

The ground is always cold at night because the

atmosphere absorbs the sun's energy at night

earth radiates heat to the atmosphere at night Correct answer

sun no longer shine at night

atmosphere reflects the sun's energy at night

Answer Details

The earth radiate heat to the atmosphere at night thereby lowering the temperature of the ground

Read lesson note on Heat Energy (WAEC)

Read lesson note on Magnetic Field (Part 1) (WAEC)

Heat Energy

Magnetic Field (Part 1)

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Question 9 Report

A copper wire was subjected to a tensile stress of 7.7 x 107 x 10 Nm-2. calculate strain of the wire.
[young modules = 1.1 x 1011 Nm-2]

2. 0 x 10-5

7.0 x 10-3

7.0 x 10-4 Correct answer

2.2 x 10-4

Answer Details

Young modules =

\frac{Tensile stress}{Tensile strain}

= $1.1 \times 10^{1} 1 = \frac{7.7 \times 10^{7}}{Tensile Strain}$

∴ Tensile strain = $\frac{7.7 \times 10^{7}}{1.1 \times 10^{1} 1}$

= $7.0 \times 10^{7 - 11} = 7.0 \times 10^{- 4}$

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Elasticity

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Question 10 Report

A man standing on a lift that is descending does not feel any weight because

the inside of the lift is air tight

the lift is in vacuum

there is no reaction from the floor of the lift Correct answer

there is no gravitational pull on the man in the lift

Answer Details

The resultant force acting on the man is given by w = mg - R
Mg - mg = 0
The man feels weightless because the reaction, R is equal to the weight mg

Read lesson note on Gravitational Field (JAMB)

Read lesson note on Gravitational Field (WAEC)

Gravitational Field

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Question 11 Report

In an A.C circuit, the ratio of r.m.s value to peak value of current is

\frac{1}{\sqrt{2}}

Correct answer

Answer Details

Irms =	I₀
	?2

Therefore	?2Irms	=	I₀
	Irms	=
	I₀		?2

Read lesson note on Simple A.C. Circuits (WAEC)

Simple A.C. Circuits

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Question 12 Report

The correct expression for the potential at a point distance r from a charge q in an electric field is

_q²

4πεor²

_q²

4πεor

4πεor²

4πεor

Correct answer

Answer Details

Electric potential is work done in taking a unit mass or charge from infinity to that point

V =	w	=	Fr	=	Q1Q2	x	r
	Q		Q		4πεor2		Q1

=	_q
	4πεor

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 13 Report

Two inductors of inductance 4 II and 8 II are arrange in series and a current of 10 A is passed through them. What is the energy stored in them?

500 J

50 J

133 J Correct answer

250 J

Answer Details

Effective inductance
(1)/L = (1)/4 + (1)/8 = (3)/8
∴ L = (8)/3
Energy stored = (1)/2 LI2
= (1)/2 x (8)/3 x 10 x 10 = (400)/3 = 133.3 J

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Capacitors

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Question 14 Report

When the human eye loses its power of accomodation, the defect is known as

short sightedness

presbyobia Correct answer

astigmatism

long sightedness

Answer Details

presbyopia is loss of accommodation

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

Read lesson note on Light Waves (WAEC)

Properties Of Waves: Reflection, Refraction, Diffraction

Light Waves

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Question 15 Report

If it takes an object 3s to fall freely to the ground from a certain height, what is the distance covered by the object?

90 m

30 m

45 m Correct answer

60 m

Answer Details

S = (1)/2gt2
S = (1)/2 x (10)/1 x 32 =5 x 9 = 45 m

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Motion

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Question 16 Report

Which of the following types of waves needs a medium for propagation?

sound waves Correct answer

light waves

radio waves

x - rays

Answer Details

Sound is the only mechanical wave among the rest which are electromagnetic waves.

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Sound Waves

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Question 17 Report

The diagram above show the positions of a cone. The position which can be described as neutral equilibrium is represented as

Z only Correct answer

X only

Y and Z

Y and X

Answer Details

Under neutral equilibrium, the body rolls and the position of the center of gravity , C. G is neither raised nor lowered

Read lesson note on Equilibrium Of Forces (WAEC)

Equilibrium Of Forces

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Question 18 Report

Steam burn is more severe than that of boiling water because

steam burn is independent of relative humidity

stem possesses greater heat energy per unit mass Correct answer

water boils at a higher temperature

steam burn is dependent on relative humidity

Answer Details

The specific latent heat of vaporization of steam is 2.1 x 106JKg-1
while the energy required to raise the temperature of a unit mass of water from 0°c to 100°c = C x Dt = 4200 x 100 = 420000 = 4.2 x 105 JKg-1
? steam possesses greater heat energy per unit mass

Read lesson note on Heat Energy (WAEC)

Heat Energy

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Question 19 Report

The phenomenon that shows that increase in pressure lowers the melting point can be observed in

sublimation

condensation

coagulation

regelation Correct answer

Answer Details

Regelation means refreezing a phenomenon whereby melted ice free from increased pressure refreezed when they are released from the pressure.

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Pressure

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Question 20 Report

An object weighs 22 kg in water and 30kg in air. what is the upthrust exerted by the liquid on the object.
[g = 10 ms2]

50 N

520 N

220 N

80 N Correct answer

Answer Details

upthrust = weight in air - weight in liquid = 30 x 10 - 22 x 10 = 300 - 220 = 80 N

Read lesson note on Measurements And Units (JAMB)

Measurements And Units

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Question 21 Report

Which of the following will be applied when a metal Y is used to electroplate another metal X in electrolysis?

X is the anode and very high current is used

X is the anode and Y is the cathode

Y is the cathode and X is the anode

Y is the anode and very high current is used Correct answer

Answer Details

Metals and hydrogen are deposited at the cathode, while non-metals and oxygen are deposited on the anode
∴ metals Y will form the anode which is deposited at the cathode made of x

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 22 Report

The bond between silicon and germanium is

covalent Correct answer

ionic

dative

electrovalent

Answer Details

Read lesson note on Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

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Question 23 Report

An image in a convex lens is upright and magnified 3 times. If the focal length of the lens is 15 cm, what is the object distance?

10 cm Correct answer

25 cm

16 cm

14 cm

Answer Details

m = v/u = -3
v = -3u
f = 15cm
1/v + 1/U = 1/f1/-3U + 1/u = 1/152/3u = 1/15
3U = 15 x 2
U = 30/3
= 10 cm

Read lesson note on Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

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Question 24 Report

In homes, electrical appliances and lamps are connected in parallel because

Parallel connections do not heat up the wires

series connections use high voltage

less current will be used

Correct answer

less voltage will be used

Answer Details

The voltage of a circuit is the same whether in parallel or in series. Parallel and series affects resistance and current. So the answer should be it uses less current.

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 25 Report

If the volume of a gas increases steadily as the temperature decreases at constant pressure, the gas obeys

Graham's Law

Boyle's Law

Correct answer

Pressure law

Charles Law

No Correct Option

Answer Details

Read lesson note on Gas Laws (JAMB)

Read lesson note on Temperature And Its Measurement (JAMB)

Gas Laws

Temperature And Its Measurement

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Question 26 Report

A machine is used to lift a load of 20 N through a height of 10 m. if the efficiency of the machine is 40%, how much work is done?

80 J

500 J Correct answer

300 J

120 J

Answer Details

Efficiency =

\frac{work output}{work input} \times \frac{100}{1}

= 40 = $\frac{20 \times 10}{x} \times \frac{100}{1}$
= 500J

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

Work, Energy And Power

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Question 27 Report

Which of the following electromagnetic waves has the highest frequency?

utra - violet rays

radio waves

x - rays Correct answer

infrared - rays

Answer Details

r - rays has the highest frequency followed by X - rays, ultraviolet ray, visible light intra - red and the least is radio weaves

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

Electromagnetic Waves: Types Of Radiation In Electromagnetic Spectrum

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Question 28 Report

I. Density of the liquid.

II. Depth below the surface of the liquid.

III. Surface area of the liquid.

In which of the statement above will pressure be dependent?

I and II only. Correct answer

II and III only.

I, II and III only.

I and III only.

Answer Details

Pressure in liquid is independent of cross sectional area of the container/ liquid
∴ the correct options are I & II

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Pressure

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Question 29 Report

Which of the following is a property of steel?

it cannot retain its magnetism longer than iron

it can be used for making temporary magnets

it can be used for making permanent magnets Correct answer

it can easily be magnetized and demagnetized

Answer Details

Steel is not easily magnetized and dismagnetized

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Magnets And Magnetic Fields

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Question 30 Report

A carpenter on top of a roof of 20.0m high dropped a hammer of mass 1.5 kg and it fell directly to the ground. the kinetic energy of the hammer just before hitting the ground is?

[g = 10 ms-2]

600 J

150J

300 J Correct answer

450 J

Answer Details

K e just before hitting the gound
= P e at the maximum height (conservation of mechanical energy)
K e = P e = mgh = 1.5 x 10 x 20
= 300 J

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

Work, Energy And Power

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Question 31 Report

In measuring high frequency a.c, the instrument used is the

d.c ammeter

moving coil ammeter

moving iron ammeter

hot wire ammeter Correct answer

Answer Details

Hot wire ammeter is used because the heat affect of A C is same as that of DC

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Question 32 Report

The electrical properties of germanium can be altered drastically by the addition of impurity. This process is referred to as

saturation

bonding

amplification

dopping Correct answer

Answer Details

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 33 Report

The capacitance of a parallel plate capacitor is 20 μf in air and 60 μf in the presence of a dielectric. What is the dielectric constant?

0.3

6.0

3.0 Correct answer

2.0

Answer Details

Dielectric constant = (c)/c° = (60)/20 = 3

Read lesson note on Capacitors (JAMB)

Capacitors

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Question 34 Report

A cannon is fired from town X,after how long is the sound heard at a town Y 4.95 km away?

[velocity of sound in the air = 330 ms-1]

30 s Correct answer

10 s

15 s

Answer Details

V = (2X)/t
330 = (2 x 4.95 x 103)/t
t = (9.9. x 103/330 = (9900)/330 = (90)/3
= 30 secs

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Motion

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Question 35 Report

I. High thermal capacity.

II. High sensitivity.

III.Easy readability.

IV. Accuracy over a wide range of temperature

From the statement above, the qualities of a good thermometer are

I and II

I, II,III and IV

I, III and IV

II, III and IV Correct answer

Answer Details

A good thermometric liquid should not have a high thermal capacity so that the themperetue of the body being measured will not be affected
? II, III and IV are qualities of a good thermometer

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 36 Report

Three similar cells each of e.m.f 2 v and internal resistance 2Ω are connected in parallel, the total e.m.f and total internal resistance are respectively

6 v, 6.0Ω

2 v, 0.7Ω Correct answer

2 v, 6.0Ω

6 v, 0.7Ω

Answer Details

Total energy in parred connection is equal to emt of one cell, = 2v but total internal resistance is given by
(1)/r = (1)/r1 + (1)/r2 + (1)/r3 = (1)/2 + (1)/2 + (1)/2 = (3)/2
∴ r = (2)/3 = 0.67Ω

Read lesson note on Capacitors (JAMB)

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Capacitors

Electric Cells

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Question 37 Report

When a red rose flower is observed in blue light, what colour does the observer see?

Red

Blue

Magenta

yellow

No correct option

Correct answer

Answer Details

The colour which an object presents to the eye is the colour of light it reflects. Red rose flower will therefore absorb any other colour and reflect red. Therefore when viewed in blue light, it has no colur to reflect and will therefore appear black. Although mixture of red light and blue light = magenta . NO correct option.

Read lesson note on Structure Of The Nucleus (WAEC)

Structure Of The Nucleus

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Question 38 Report

A length of wire has a frequency of 255Hz when stretched by a force of b225N. If the fore increased to 324N, what is the new frequency of vibration

306 Hz Correct answer

512 Hz

488 Hz

356 Hz

Answer Details

f1 = 255Hz, T1 = 225N
f2 = ? T2 = 324N
But f ∝ √T => f = K√T
=> K = f/√T
∴ f1/√T1 = f2/√T2225/√225 = f2/√324

f2 =	225√225
	√225

=	225 x 18
	__15

= 306Hz

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Read lesson note on Equilibrium Of Forces (WAEC)

Motion

Equilibrium Of Forces

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Question 39 Report

The eclipse of the sun occurs when the

moon is between the sun and the earth
Correct answer

earth is between the sun and the moon

moon is not completely hidden in the earth's shadow

moon's umbra falls on some part of the earth

Answer Details

Eclipse of the sun occurs when the moon which is opaque objects between the sun and the earth

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Read lesson note on Electromagnetic Field (Part 2) (WAEC)

Description Property Of Fields

Electromagnetic Field (Part 2)

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Question 40 Report

Which of the following materials has an increase in resistance with temperature?

water

metals Correct answer

wood

electrolyte

Answer Details

Resistance in metals are proportional to temperature

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 41 Report

A block of aluminum is heated electrically by a 25 W heater. if the temperature rises by 10°C in 5 minutes, the heat capacity of the aluminum is?

850 JK-1

750 JK-1 Correct answer

650 JK-1

500 JK-1

Answer Details

Heat supplied = Heat gained
P x t = C ∆ Ø
(25 x 5 x 60)/300 = 750 JK-1

Read lesson note on Heat Energy (WAEC)

Heat Energy

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Question 42 Report

The diagram above shows two vectors at right angles to each other. The value of the resultant vector is

14.0 N

10.0 N Correct answer

12.0 N

13.0 N

Answer Details

The resultant, R is given by pythagoras rule, R2 = P2 + Q2
= 62 + 82 = 36 + 64 = 100
R = √100 = 10.0N

Read lesson note on Scalars And Vectors (WAEC)

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Scalars And Vectors

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Question 43 Report

A certain far - sighted person cannot see object that are closer to the eye than 50 cm clearly. Determine the power of the converging lens which will enable him to see at 25 cm

0.06 D

0.02 D

0.03 D

0.04 D

no option is correct

Correct answer

Answer Details

V = - 50, U = 25CM
(1)/r = (1)/v + (1)/u = (1)/-50 + (1)/25 = (1 + 2)/50 = (1)/50 f = +50cm = +0.5m
p = (1)/r = (1)/0.5 = (10)/5 = 2 diopters
The power of a lens is the reciprocal of the focal length in meters. it is expressed in diopters.

Read lesson note on Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

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Question 44 Report

If the threshold frequency for tungsten is 1.3 x 1015Hz, what is its work function?
[H = 6.6 x 10-34 Js]

8.58 x 10-19 J Correct answer

8.50 x 10-15 J

8.58 x 10-17 J

8.85 x 10-18

Answer Details

Work function, w = hfo 6.6 x 10-34 x 1.3 x 1015
= 8.58 x 10-19

Read lesson note on Structure Of The Atom (Nigeria Only) (WAEC)