The drift velocity of free electrons in a conductor is \(v\) when a current \(i\) is flowing in it. If both the radius and current are doubled, then the drift velocity will be:

1. \(v\) 2. \(\dfrac{v}{2}\)
3. \(\dfrac{v}{4}\) 4. \(\dfrac{v}{8}\)

Subtopic:  Current & Current Density |
 73%
From NCERT
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A battery has emf \(4\) V and internal resistance \(r\). When this battery is connected to an external resistance of \(2\) ohm, a current of \(1\) ampere flows in the circuit. How much current will flow if the terminals of the battery are connected directly?
1. \(1\) A 2. \(2\) A
3. \(4\) A 4. Infinite
Subtopic:  EMF & Terminal Voltage |
 66%
From NCERT
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The current \(I\) as shown in the circuit will be:

1. \(10~\text{A}\) 2. \(\dfrac{20}{3}~\text{A}\)
3. \(\dfrac{2}{3}~\text{A}\) 4. \(\dfrac{5}{3}~\text{A}\)
Subtopic:  Combination of Resistors |
 61%
From NCERT
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A meter bridge is set up to determine unknown resistance \(x\) using a standard \(10~\Omega\) resistor. The galvanometer shows the null point when the tapping key is at a \(52\) cm mark. End corrections are \(1\) cm and \(2\) cm respectively for end \(A\) and \(B\). Then the value of \(x\) is:

      
1. \(10.2~\Omega\)
2. \(10.6~\Omega\)
3. \(10.8~\Omega\)
4. \(11.1~\Omega\)

Subtopic:  Meter Bridge & Potentiometer |
 52%
From NCERT
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The resistivity of iron is 1 × 10–7 ohm m. The resistance of iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in ohm m will be :

(1) 1 × 10–7

(2) 2 × 10–7

(3) 4 × 10–7

(4) 8 × 10–7

Subtopic:  Derivation of Ohm's Law |
 67%
From NCERT
PMT - 1983
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The resistivity of a wire :

1. Increases with the length of the wire
2. Decreases with the area of cross-section
3. Decreases with the length and increases with the cross-section of the wire
4. None of the above statement is correct
Subtopic:  Derivation of Ohm's Law |
 73%
From NCERT
PMT - 1984
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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 |
 90%
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) 1ρ

(2) 3ρ

(3) 1ρ3

(4) ρ13 

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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