2011 - JAMB Physics Past Questions and Answers - page 3
21
Steam burn is more severe than that of boiling water because
A
steam burn is independent of relative humidity
B
stem possesses greater heat energy per unit mass
C
water boils at a higher temperature
D
steam burn is dependent on relative humidity
correct option: b
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
Users' Answers & Commentswhile 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
22
I. change of state
II. Diffusion
III. Radiation
IV. Osmosis
which of the processes above can be explained using the kinetic theory?
II. Diffusion
III. Radiation
IV. Osmosis
which of the processes above can be explained using the kinetic theory?
A
I, II,III and IV
B
I, II and III
C
I, III and IV
D
I, II and IV
correct option: d
Users' Answers & Comments23
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
A
6 v, 6.0Ω
B
2 v, 0.7Ω
C
2 v, 6.0Ω
D
6 v, 0.7Ω
correct option: b
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
Users' Answers & Comments(1)/r = (1)/r1 + (1)/r2 + (1)/r3 = (1)/2 + (1)/2 + (1)/2 = (3)/2
∴ r = (2)/3 = 0.67Ω
24
When the human eye loses its power of accomodation, the defect is known as
A
short sightedness
B
presbyobia
C
astigmatism
D
long sightedness
25
When a red rose flower is observed in blue light, what colour does the observer see?
A
Red
B
Blue
C
Magenta
D
yellow
correct option: e
Correct Answer: Option E
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.
Users' Answers & Comments26
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?
A
0.3
B
6.0
C
3.0
D
2.0
27
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
A
0.06 D
B
0.02 D
C
0.03 D
D
0.04 D
correct option: e
Correct Answer: Option E
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.
Users' Answers & Comments(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.
28
The eclipse of the sun occurs when the
A
moon is between the sun and the earth
B
earth is between the sun and the moon
C
moon is not completely hidden in the earth's shadow
D
moon's umbra falls on some part of the earth
correct option: a
Eclipse of the sun occurs when the moon which is opaque objects between the sun and the earth
Users' Answers & Comments29
Which of the following is a property of steel?
A
it cannot retain its magnetism longer than iron
B
it can be used for making temporary magnets
C
it can be used for making permanent magnets
D
it can easily be magnetized and demagnetized
30
In measuring high frequency a.c, the instrument used is the
A
d.c ammeter
B
moving coil ammeter
C
moving iron ammeter
D
hot wire ammeter
correct option: d
Hot wire ammeter is used because the heat affect of A C is same as that of DC
Users' Answers & Comments