# Physics 2011 | Study Mode

Question 21
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
##### Explanation
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 0c to 100c = C x Dt = 4200 x 100 = 420000 = 4.2 x 105 JKg-1
steam possesses greater heat energy per unit mass

Question 22
A
I, II,III and IV
B
I, II and III
C
I, III and IV
D
I, II and IV

Question 23
A
6 v, 6.0
B
2 v, 0.7
C
2 v, 6.0
D
6 v, 0.7
##### Explanation
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 = 0.67

Question 24
A
short sightedness
B
presbyobia
C
astigmatism
D
long sightedness
##### Explanation
presbyopia is loss of accommodation

Question 25
A
Red
B
Blue
C
Magenta
D
yellow
E
No correct option
##### Explanation
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.

Question 26
A
0.3
B
6
C
3
D
2
##### Explanation
Dielectric constant = (c)/c = (60)/20 = 3

Question 27
A
0.06 D
B
0.02 D
C
0.03 D
D
0.04 D
E
no option is correct
##### Explanation
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.

Question 28
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
##### Explanation
Eclipse of the sun occurs when the moon which is opaque objects between the sun and the earth

Question 29
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
##### Explanation
Steel is not easily magnetized and dismagnetized

Question 30
A
d.c ammeter
B
moving coil ammeter
C
moving iron ammeter
D
hot wire ammeter
##### Explanation
Hot wire ammeter is used because the heat affect of A C is same as that of DC

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