CURRENT ELECTERCITY
Important short questionsQ13.1 A potential difference is applied across the ends of a Copper wire .what is the effect on the drift velocity of electrons.
Answer:
Increase the potential difference
decrease in the length and temperature of wire.
drift velocity is the actual resultant velocity of the electrons in the presence of an external electric field.
Q13.2
Do bends in the a wire effects its electrical resistance explain?
Answer: no as we know,R pL/A IT SHOWS THAT THERE IS NO RELATIONSHIP b/w resistance and and the bends of a wire.Hence bend in a wire do not affect the resistance of a wire.
Q13.3
Why the resistance of conductor rise with temperature?
Actually resistance of the conductor is due to collision b/w electrons and and lattice atoms,with increase in the temperature,vibration motion of atoms increases and due to greater Amplitude of vibration,their collision probability increases hence resistance of the conductor increases.
Q13.4
What are the Difficulities in testing the filament of bulb wheather it obeys ohm law or not?
The resistance of the lighted bulb do not remain constant but gradually increase with increase in temperature , so the filament of the bulb do not obey,s ohm law.
Q13.5 what is Wheatstone bridge.How can we measure a unknown resistance ?
The device which is used to measure a unknown resistance is called Wheatstone Bridge.
An unknown resistance can be found by this relation
R1/R2=R3/R4
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