Physics-1999-Set-I

Q1) Draw an equipotential surface in a uniform electric field. (Marks 1)
Ans1)

Equipotential surfaces are parallel planes perpendicular to the field lines.

Q2) If a wire is stretched to double its original length without less of mass, how will the resistivity of the wire be influenced? (Marks 1)
Ans2) The resistivity of the wire will remain same as it is the resistance of wire of unit length & unit cross-sectional area.

Q3) Why do magnetic lines of force prefer to pass through iron than through air? (Marks 1)
Ans3) The magnetic lines of force prefer to pass through iron then through air as iron has very high magnetic permeability.

Q4) What is the power factor of an LCR series circuit at resonance? (Marks 1)
Ans4) Power factor cos = R/(R2 + (L – 1/c)2)
At resonance L = 1/c
… cos = R/(R2 + 0) = 1

Q5) Why is the transmission of signals using ground waves restricted to frequencies upto 1500 kHz? (Marks 1)
Ans5) The transmission of signals using ground wave is restricted to frequencies upto 1500 kHz because higher frequencies are damped by interaction with matter.

Q6) The polarising angle of a medium is 60o. What is the refractive index of the medium? (Marks 1)
Ans6) = tan ip
ip = 60o
… = tan 60o = 3

  1. Ankur
    November 30th, 2009 at 04:28 | #1

    Give me the physics paper

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