JAMB UTME - Physics - 2011
Swali 1 Ripoti
The diagram above shows two vectors at right angles to each other. The value of the resultant vector is
Maelezo ya Majibu
The resultant, R is given by pythagoras rule, R2 = P2 + Q2
= 62 + 82 = 36 + 64 = 100
R = √100 = 10.0N
Swali 3 Ripoti
The phenomenon that shows that increase in pressure lowers the melting point can be observed in
Maelezo ya Majibu
Regelation means refreezing a phenomenon whereby melted ice free from increased pressure refreezed when they are released from the pressure.
Swali 4 Ripoti
In measuring high frequency a.c, the instrument used is the
Maelezo ya Majibu
Hot wire ammeter is used because the heat affect of A C is same as that of DC
Swali 5 Ripoti
In homes, electrical appliances and lamps are connected in parallel because
Maelezo ya Majibu
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.
Swali 6 Ripoti
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
Maelezo ya Majibu
Swali 7 Ripoti
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?
Maelezo ya Majibu
Dielectric constant = (c)/c° = (60)/20 = 3
Swali 8 Ripoti
Which of the following materials has an increase in resistance with temperature?
Maelezo ya Majibu
Resistance in metals are proportional to temperature
Swali 9 Ripoti
Which of the following will be applied when a metal Y is used to electroplate another metal X in electrolysis?
Maelezo ya Majibu
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
Swali 10 Ripoti
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?
Maelezo ya Majibu
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
Swali 11 Ripoti
In an A.C circuit, the ratio of r.m.s value to peak value of current is
Maelezo ya Majibu
| Irms = | I0 |
| ?2 | |
| Therefore | ?2Irms | = | I0 |
| Irms | = | 1 | |
| I0 | ?2 |
Swali 12 Ripoti
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
Maelezo ya Majibu
| I | V |
| R |
| = | 12 |
| 12 |
= 1A
Swali 13 Ripoti
A perfect emitter or absorber of radiant energy is a
Maelezo ya Majibu
Dull, black surface are good emitters or absorbers of energy
Swali 14 Ripoti
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
Maelezo ya Majibu
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
Swali 15 Ripoti
A metal of volume 40 cm3 is heated from 30 °c to 90 °c, the increase in volume is
Maelezo ya Majibu
increase in volume, DV = RV1 ∆ θ = 3α Vsub>1 Dθ
= 3 x 2.0 X 10-5 x 40 x (90 - 30)
= 6 x 10-5 x 40 x 60
0.144 cm3
∴ No correct option
Swali 16 Ripoti
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?
Maelezo ya Majibu
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.
Swali 17 Ripoti
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?
Maelezo ya Majibu
Efficiency = work outputwork input×1001
= 40 = 20×10x×1001
= 500J
Swali 18 Ripoti
When the human eye loses its power of accomodation, the defect is known as
Maelezo ya Majibu
presbyopia is loss of accommodation
Swali 19 Ripoti
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
Maelezo ya Majibu
Centripetal force,
F = mv2r
= 2×1024
= 2004
= 50N
Swali 20 Ripoti
If the threshold frequency for tungsten is 1.3 x 1015Hz, what is its work function?
[H = 6.6 x 10-34 Js]
Maelezo ya Majibu
Work function, w = hfo 6.6 x 10-34 x 1.3 x 1015
= 8.58 x 10-19
Swali 21 Ripoti
The diagram above show the positions of a cone. The position which can be described as neutral equilibrium is represented as
Maelezo ya Majibu
Under neutral equilibrium, the body rolls and the position of the center of gravity , C. G is neither raised nor lowered
Swali 22 Ripoti
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
Maelezo ya Majibu
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
Swali 23 Ripoti
When a red rose flower is observed in blue light, what colour does the observer see?
Maelezo ya Majibu
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.
Swali 24 Ripoti
If the volume of a gas increases steadily as the temperature decreases at constant pressure, the gas obeys
Maelezo ya Majibu
Swali 25 Ripoti
Which of the following could be effectively used to reduce friction?
Maelezo ya Majibu
grease is more viscous than the rest of the liquids
Swali 26 Ripoti
A man standing on a lift that is descending does not feel any weight because
Maelezo ya Majibu
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
Swali 27 Ripoti
If the charge of electricity is K wh is N4, what is the cost of operating an electrical appliance rated 250 v,2 A for six hours?
Maelezo ya Majibu
Energy consumed = power x time = lvt = 2 x 250 x 6hr = 300 wh = 3 kwh but 1 kwh = N4
3 kwh = 3 x N4 = N 12
Swali 28 Ripoti
The correct expression for the potential at a point distance r from a charge q in an electric field is
Maelezo ya Majibu
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 |
Swali 29 Ripoti
Which of the following types of waves needs a medium for propagation?
Maelezo ya Majibu
Sound is the only mechanical wave among the rest which are electromagnetic waves.
Swali 30 Ripoti
Which of the following is a property of steel?
Maelezo ya Majibu
Steel is not easily magnetized and dismagnetized
Swali 31 Ripoti
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]
Maelezo ya Majibu
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
Swali 32 Ripoti
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?
Maelezo ya Majibu
Heat supplied = Heat gained
P x t = C ∆ Ø
(25 x 5 x 60)/300 = 750 JK-1
Swali 33 Ripoti
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?
Maelezo ya Majibu
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
Swali 34 Ripoti
A radioactive isotope has a decay constant of 10-5s4. Calculate half life
Maelezo ya Majibu
T (1)/2 = (0.693)/λ = (0.693)/10-5
= 0.693 x 105
= 6.93 x 104 sec
Swali 35 Ripoti
The eclipse of the sun occurs when the
Maelezo ya Majibu
Eclipse of the sun occurs when the moon which is opaque objects between the sun and the earth
Swali 36 Ripoti
The electrical properties of germanium can be altered drastically by the addition of impurity. This process is referred to as
Maelezo ya Majibu
Swali 37 Ripoti
If a tube of small radius opened at both ends is placed in a liquid, the liquid will
Maelezo ya Majibu
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
Swali 38 Ripoti
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]
Maelezo ya Majibu
V = (2X)/t
330 = (2 x 4.95 x 103)/t
t = (9.9. x 103/330 = (9900)/330 = (90)/3
= 30 secs
Swali 39 Ripoti
The ground is always cold at night because the
Maelezo ya Majibu
The earth radiate heat to the atmosphere at night thereby lowering the temperature of the ground
Swali 40 Ripoti
Which of the following electromagnetic waves has the highest frequency?
Maelezo ya Majibu
r - rays has the highest frequency followed by X - rays, ultraviolet ray, visible light intra - red and the least is radio weaves
Swali 41 Ripoti
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
Maelezo ya Majibu
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.
Swali 42 Ripoti
I. change of state
II. Diffusion
III. Radiation
IV. Osmosis
Which of the processes above can be explained using the kinetic theory?
Maelezo ya Majibu
Swali 43 Ripoti
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]
Maelezo ya Majibu
Young modules = Tensile stressTensile strain
= 1.1×1011=7.7×107Tensile Strain
∴ Tensile strain = 7.7×1071.1×1011
= 7.0×107−11=7.0×10−4
Swali 44 Ripoti
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?
Maelezo ya Majibu
Pressure in liquid is independent of cross sectional area of the container/ liquid
∴ the correct options are I & II
Swali 45 Ripoti
If it takes an object 3s to fall freely to the ground from a certain height, what is the distance covered by the object?
Maelezo ya Majibu
S = (1)/2gt2
S = (1)/2 x (10)/1 x 32 =5 x 9 = 45 m
Swali 46 Ripoti
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
Maelezo ya Majibu
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
Swali 47 Ripoti
Steam burn is more severe than that of boiling water because
Maelezo ya Majibu
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
Swali 48 Ripoti
Under which of the following conditions do gases conduct electricity?
Maelezo ya Majibu
Under high potential difference and low pressure gases are good conductor of electricity
Swali 50 Ripoti
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]
Maelezo ya Majibu
upthrust = weight in air - weight in liquid = 30 x 10 - 22 x 10 = 300 - 220 = 80 N
