# Physics 2008 | Study Mode

Question 21
A
I and IV only
B
II and IV only
C
I and III only
D
III and IV only
##### Explanation
Due to rectilinear propagation of light we have ecslipse which occur as a result relative motion of the earth, sun and moon

Question 22
A
3.0 cm
B
8.0 cm
C
12.0 cm
D
16.0 cm
##### Explanation
Magnification = (image height)/object height
= (lenght camera)/object distance from pin-hole
(2)/4 = (6)/X
X (4 x 6)/2 = 12 cm

Question 23
A
20 cm
B
15 cm
C
10 cm
D
5 cm
##### Explanation
(1)/V + (1)/U = (1)/f
(1)/V + (1)/20 = (1)/10
(1)/V = (1)/10 - (1)/20 = (2 -1)/20 = (1)/20
V = 20 cm
mag = (image height)/object height = (v)/u
(X)/5 = (20)/50
X = 5 cm

Question 24
A
erect, virtual and diminished
B
erect, real and diminished
C
erect, virtual and magnified
D
inverted virtual and diminished
##### Explanation
Image formed by convex mirror is always erect, virtual and diminished

Question 25
A
diffraction
B
reflection
C
refraction
D
polarization
##### Explanation
Real depth and apparent dept is due to refraction

Question 26
A
an inverter
B
a refiner
C
a diminisher
D
a magnifier
##### Explanation
The basic function of microscope is magnification

Question 27
A
-6
B
-5
C
5
D
6
##### Explanation
Angular magnification, M = ((D)/F + 1) where D is least distance of distinct vision
M = ((25)/5 + 1) = -6

Question 28
A
generate more friction
B
ensure the balancing of the tanker
C
caution the driver when overspeeding
D
conduct excess charges to the car
##### Explanation
The friction between the tanker and air creates charges which the chain conducts to the ground.

Question 29
A
11:1
B
1:11
C
12:11
D
11:12
##### Explanation
Power supplied = IE = 20 X 240 = 4800 W
Power dissipated = IV = 20 X 220 = 4400 W
(Power supplied)/Power dissipated = (4800 W)/4400 W
= (12)/11

Question 30
A
0.96 kWh
B
19.2 kWh
C
9.60 kWh
D
19.20 kWh
##### Explanation
Energy consumed = power x time
= (60 W x 10 + 40 W x 5) x 24 h
= (600 W + 200 W ) x 24 h
= 800 W x 24h = 19200 w h
= 19.2 kWh

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