What length of the wire of specific resistance 48×108Ω  mis needed to make the resistance of 4.2 Ω (diameter of wire = 0.4 mm

(1) 4.1 m

(2) 3.1 m

(3) 2.1 m

(4) 1.1 m

Subtopic:  Derivation of Ohm's Law |
 64%
From NCERT
PMT - 2000
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A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of 

(1) Each of these increases

(2) Each of these decreases

(3) Copper strip increases and that of germanium decreases

(4) Copper strip decreases and that of germanium increases

Subtopic:  Derivation of Ohm's Law |
 65%
From NCERT
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The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter, the change in the resistance of the wire will be :

(1) 300%

(2) 200%

(3) 100%

(4) 50%

Subtopic:  Derivation of Ohm's Law |
 55%
From NCERT
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Express which of the following setups can be used to verify Ohm’s law 

(1)  
(2)
(3)
(4)
Subtopic:  Derivation of Ohm's Law |
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In a hydrogen discharge tube, it is observed that through a given cross-section 3.13 × 1015 electrons are moving from right to left and 3.12 × 1015 protons are moving from left to right per sec. What is the electric current in the discharge tube and what is its direction :

(1) 1 mA towards the right

(2) 1 mA towards left

(3) 2 mA towards left

(4) 2 mA towards the right

Subtopic:  Current & Current Density |
 63%
From NCERT
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The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then :

(1) The resistance will be doubled and the specific resistance will be halved

(2) The resistance will be halved and the specific resistance will remain unchanged

(3) The resistance will be halved and the specific resistance will be doubled

(4) The resistance and the specific resistance, will both remain unchanged

Subtopic:  Derivation of Ohm's Law |
 80%
From NCERT
PMT - 2004
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The following four wires are made of the same material and are at the same temperature. Which one of them has highest electrical resistance :

(1) Length = 50 cm, diameter = 0.5 mm

(2) Length = 100 cm, diameter = 1 mm

(3) Length = 200 cm, diameter = 2 mm

(4) Length = 300 cm, diameter = 3 mm

Subtopic:  Derivation of Ohm's Law |
 71%
From NCERT
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The potential difference between points A and B of the adjoining figure is

(1) 23V

(2) 89V

(3) 43V

(4) 2 V

Subtopic:  Combination of Resistors |
 57%
PMT - 1991
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Two resistors of resistance R1 and R2 having R1 > R2 are connected in parallel. For equivalent resistance R, the correct statement is :

(1) R>R1+R2

(2) R1<R<R2

(3) R2<R<(R1+R2)

(4) R < R1

Subtopic:  Combination of Resistors |
 66%
From NCERT
PMT - 1978
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A wire of resistance \(R\) is divided into \(10\) equal parts. These parts are connected in parallel, the equivalent resistance of such connection will be:
1. \(0.01R\)
2. \(0.1R\)
3. \(10R\)
4. \(100R\)

Subtopic:  Combination of Resistors |
 64%
From NCERT
PMT - 1973
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