A wire of 5Ω resistance is drawn out so that its new length is two times the original length. If the resistivity of the wire remains the same and the cross-sectional area is halved, the new resistance is
A40Ω
B20Ω
C10Ω
D5Ω
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Question 1322
jamb2003
I the diagram above, what would happen to the current I, if another resistor, R2, is connected in parallel to R1?
AIt will increase because the equivalent resistance will increase
BIt will decrease if R2 is greater than R1
CIt will increase because the effective resistance will decrease
DIt will decrease if R2 is less than R1
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Question 1323
jamb2003
The operation of an optical fibre is based on the principal of
Adispersion of light
Binterference of light
Crefraction of light
Dpolarization of light
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Question 1324
jamb2003
In the diagram above, if each of the resistors can dissipate a maximum of 18W without becoming excessively heated, what is the maximum power the circuit can dissipate?
A27W
B18W
C9W
D5W
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Question 1325
jamb2003
A positive charged rod X is brought near as uncharged metal sphere Y and is then touched by a finger with X still in place. When the finger is removed, the result is that y has
Ano charge and a zero potential
Ba positive charge and zero potential
Ca negative charge and positive potential
Da negative charge and a negative potential
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Question 1326
jamb2003
If 1.2 x 10^6J of heat energy is given off in 1 sec from a vessel maintained at a temperature gradient of 30Km-1, the surface area of the vessel is
[ thermal conductivity of the vessel = 400Wm-1K-1]
A1.0 x 102m2
B9. 0 x 102m2
C1.0 x 103m2
D9.0 x 104m2
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Question 1327
jamb2003
A 2000W electric heater is used to heat a metal object of mass 5kg initially at 10oC. If a temperature rise of 30oC is obtained after 10min, the heat capacity of the material is
A6.0 x 104JoC-1
B4.0 x 104JoC-1
C1.2 x 104JoC-1
D8.0 x 103JoC-1
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Question 1328
jamb2003
If the distance from a point source of sound is doubled, by what factor does the intensity decrease?
A4.00
B2.00
C0.50
D0.25
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Question 1329
jamb2003
At what position will an object be placed in front of a concave mirror in order to obtain an image at infinity?
AAt the pole of the mirror
BAt the principal focus
Cat the center of the curvature
DBetween the principal focus and the center of curvature
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Question 1330
jamb2003
The phenomenon where by the water droplets in the atmosphere combines with dust particles in the air to reduce visibility is
Acloud
Bmist
Chail
Dfog
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Question 1331
jamb2003
If an object is placed between two parallel plane mirrors with their reflecting surfaces facing each other, how many images of the object will be formed?
AInfinite
BEight
CFour
DTwo
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Question 1332
jamb2003
On a fairly cool rainy day when the temperature is 20oC, the length of a steel railroad track is 20m. What will be its length on a hot a dry day when the temperature is 40oC?
[coefficient of linear expansion of steel = 11 x 10-6K-1]
A20.013m
B20.009m
C20.004m
D20.002m
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Question 1333
jamb2003
An open pipe closed at one end produces its first fundamental note. If the velocity of sound in air is P and t the length of the pipe, the frequency of the note is
A2v/t
Bv/5t
Cv/4t
Dv/2t
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Question 1334
jamb2003
Thermal equilibrium between two object exist when
Athe temperature of both objects are equal
Bthe quantity of heat of both objects is the same
Cthe heat capacities of both objects are the same
Done object losses heat continuously to the other
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Question 1335
jamb2003
By what factor will the size of an object placed 10cm from a convex lens be increased if the image is seen on a screen placed 25cm from the lens?
A15.0
B2.5
C1.5
D0.4
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Question 1336
jamb2003
A turning fork of frequency 340Hz is vibrated just above a cylindrical tube of height 1.2m. If water is slowly poured into the tube, at what maximum height will resonance occur.
[speed of sound in air = 340ms-1]
A0.95m
B0.60m
C0.50m
D0.45m
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Question 1337
jamb2003
TºC
0
5
10
15
20
40
60
S.V.P(mmHg)
4.58
6.51
8.94
12.67
17.50
55.10
149.00
The table above shows the saturation vapour pressure against temperature in a certain town. If the vapour pressure in this town at 20oC is 10mmHg, what is the relative humidity?
A170.0%
B57.0%
C17.5%
D10.0%
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Question 1338
jamb2003
A satellite is in a parking orbit if its period is
Aless than the period of the earth
Bmore than the period of the earth
Cequal to the period of the earth
Dthe square of the period of the earth
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Question 1339
jamb2003
A 90cm uniform lever has a load of 30N suspended at 15cm from one of its ends. If the fulcrum is at the center of gravity, the force that must be applied at its other end to keep it in horizontal equilibrium is
A15N
B20N
C30N
D60N
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Question 1340
jamb2003
A piece of stone attached to one end of a string is whirled round in a horizontal circle and the string suddenly cuts. The stone will fly off in a direction
