The most suitable cell used for short interval switches in electric bells is a
Alead- acid accumulator
BDaniel cell
CLeclanche cell
Dnickel iron accumulator
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Question 662
jamb2003
Which of the following pairs of light rays show the widest separation in the spectrum of white light
ABlue and red
BGreen and yellow
CIndigo and violet
DOrange and red
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Question 663
jamb2003
I It retains its magnetic much longer than steel.
II It is more easily magnetized than steel
III It is more easily demagnetized than steel
IV It produces a stronger magnet than steel
Which combination of the above makes iron preferable to steel in the making of electromagnets?
AI and II only
BII and III only
CI, III, and IV only
DII, III and IV only
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Question 664
jamb2003
A magnetic field is said to exist at a point if a force is
Aexerted on a stationary charge at the point
Bexerted on a moving charge at the point
Cdeflected at the point
Dstrengthened at the point
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Question 665
jamb2003
An electron of charge 1.6 x 10-19C is accelerated between two metal plates. If the kinetics energy of the electron is 4.8 x 10-17J, the potential difference between the plate is
A30V
B40V
C300V
D400V
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Question 666
jamb2003
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 667
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 668
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 669
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 670
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 671
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 672
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 673
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 674
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 675
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 676
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 677
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 678
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 679
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 680
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?
