# Drift velocity $$v_d$$ varies with the intensity of electric field as per the relation: 1. $$v_{d} \propto E$$ 2. $$v_{d} \propto \frac{1}{E}$$ 3. $$v_{d}= \text{constant}$$ 4. $$v_{d} \propto E^2$$

Subtopic:  Current & Current Density |
78%
From NCERT
PMT - 1981
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In a conductor 4 coulombs of charge flows for 2 seconds. The value of electric current will be :

(1) 4 volts

(2) 4 amperes

(3) 2 amperes

(4) 2 volts

Subtopic:  Current & Current Density |
89%
From NCERT
PMT - 1984
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The specific resistance of a wire is ρ, its volume is 3 m3 and its resistance is 3 ohms, then its length will be

(1) $\sqrt{\frac{1}{\rho }}$

(2) $\frac{3}{\sqrt{\rho }}$

(3) $\frac{1}{\rho }\sqrt{3}$

(4) $\rho \sqrt{\frac{1}{3}}$

Subtopic:  Derivation of Ohm's Law |
80%
From NCERT
PMT - 1984
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When a piece of aluminum wire of finite length is drawn through a series of dies to reduce its diameter to half its original value, its resistance will become :

(1) Two times

(2) Four times

(3) Eight times

(4) Sixteen times

Subtopic:  Derivation of Ohm's Law |
From NCERT
AIIMS - 2002
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Through a semiconductor, an electric current is due to drift off:

(1) Free electrons

(2) Free electrons and holes

(3) Positive and negative ions

(4) Protons

Subtopic:  Current & Current Density |
74%
From NCERT
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If a metallic block has no potential difference applied across it, then the mean velocity of free electron is:
($$T$$= absolute temperature of the block)
 1 proportional to $$T$$. 2 proportional to$$\sqrt{T}$$ 3 zero. 4 finite but independent of temperature.
Subtopic:  Current & Current Density |
52%
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The specific resistance of all metals is most affected by :

(1) Temperature

(2) Pressure

(3) Degree of illumination

(4) Applied magnetic field

Subtopic:  Derivation of Ohm's Law |
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The positive temperature coefficient of resistance is for :

(1) Carbon

(2) Germanium

(3) Copper

(4) An electrolyte

Subtopic:  Current & Current Density |
67%
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The electric intensity E, current density j and specific resistance k are related to each other by the relation :

(1) E = j/k

(2) E = jk

(3) E = k/j

(4) k = jE

Subtopic:  Current & Current Density |
67%
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The resistance of a wire of uniform diameter d and length L is R. The resistance of another wire of the same material but diameter 2d and length 4L will be :

(1) 2R

(2) R

(3) R/2

(4) R/4

Subtopic:  Derivation of Ohm's Law |
74%
From NCERT
PMT - 1984
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