Which of the following may be used to explain a mirage? i. layers of air near the road surface have varying refractive indices in hot weather. ii. road surfaces sometimes become good reflectors in hot weathers. iii. ligh…
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1993
If the focal length of a camera lens is 20cm, the distance from the film at which the lens must be set to produce a sharp image of an object 100cm away is
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1993
Which of the following expressions gives the linear magnification produced by a concave mirror of radius of curvature r, if U and V are the object and image distances respectively?
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1993
The terminal voltage of a battery is 4.0V when supplying a current of 2.0A, and 2.0V when supplying a current of 3.0A. The internal resistance of the battery is
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1993
A simple cell with mercury-amalgamated zinc electrode prevents
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1993
A current carrying conductor experiences a force when placed in a magnetic field because the
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1993
Which of the following correctly explains why soft iron is proffered to steel in electromagnets? i. soft iron is more readily magnetized than steel. ii. soft iron is more readily demagnetized than steel. iii. soft iron r…
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1993
Which of the following correctly explain(s) why a green leaf appears green in bright day light? i. it absorbs only the green component of sunlight. ii. it absorbs all colour of sunlight except green. iii. it reflects onl…
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1993
The primary aim in high tension transmission is to
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1993
Which of the following devices may be used to step up the voltage in a d.c. circuit?
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1993
A 40-W instrument has a resistance of 90\(\Omega\). On what voltage should it be operated normally?
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1993
A parallel plate capacitor of area 10cm2 in vacuum has a capacitance of 10-2\(\mu\)F. What is the distance between the plates?(e = 9 x 10-12fm)
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1993
A current of 100mA passes through a conductor for 2 minutes. The quantity of electricity transported is
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1993
An element X of an atomic number 88 and mass number 226 decays to form an element Z by emitting two beta particles and an alpha particle. Z is represented by
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1993
Which of the following are produced after a nuclear fusion process? i. one heavy nucleus. ii. neutrons-1. iii. protons. iv. Energy.
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1993
Natural radioactivity is the random spontaneous disintegration of the nuclei of heavy isotopes of certain elements with the emission of
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1993
Which of the following statements correctly describe(s) cathode rays? i. they consist of tiny particles carrying negative electric charges. ii. they are deflected in a magnetic field but not in an electric field. iii. th…
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1993
Determine the inductive reactance when a 30.0mH inductor with a negligible resistance is connected to a 1.3 x 103Hz oscillator.
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1993
The kinetic theory of photoelectron liberated from a metallic surface depends on the
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1993
In the figure above, a lever of length 200m is used to lift a load of mass 180kg. The pivot at P is 20m from the load. what minimum force F must be applied at the end of the lever [g = 10ms-2]