The resistance of a platinum wire at 0°C is 22.05Ω and at 100°C it becomes 22.70Ω. When the wire is heated to a temperature of t°C the resistance of wire becomes 24.91Ω. The value of t is

1.  220

2.  440

3.  310

4.  550

Concept Questions :-

Derivation of Ohm's law
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Two wire A and B of copper have equal masses and the lengths are 10cm and 20cm respectively. If resistance of A be RA and B be RB, then the value of RARB is  

1.  12 

2.  2 

3.  14 

4.   4

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The sensitivity of a potentiometer can be increased by

1.  increasing the potential gradient

2.  decreasing the length of potentiometer wire

3.  decreasing the current in the potentiometer wire

4.  all of these

Concept Questions :-

Meter bridge and potentiometer
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In the circuit shown in  figure if power dissipated in 9Ω resistor is 144W, then potential difference across 3.6Ω resistor will be

                                                 

1.  36V

2.  18V

3.  9V

4.  Zero

Concept Questions :-

Heating effect of current
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A current of 1 mA is flowing through a copper wire. How many electrons will pass a given point in one second  e = 1.6 × 10-19 Coulomb

1.  6.25 × 1019  

2.  6.25 × 1015  

3.  6.25 × 1031  

4.  6.25 × 108

Concept Questions :-

Current and current density
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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 drift velocity will be :

1.  v

2.  v2 

3.  v4 

4.  v8

Concept Questions :-

Current and current density
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A battery has e.m.f. 4V and internal resistance r. When this battery is connected to an external resistance of 2 ohms, a current of 1 amp. flows in the circuit. How much current will flow if the terminals of the battery are connected directly

1.  1 Amp

2.  2 Amp

3.  4 Amp

4.  Infinite

Concept Questions :-

Emf and terminal voltage
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Three copper wires have their lengths in the ratio 5:3:1 and their masses are in the ratio 1:3:5. Their electrical resistance will be in the ratio of :

1. 5:3:1

2. 1:3:5

3. 125:15:1

4. 1:15:125

Concept Questions :-

Derivation of Ohm's law
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The equivalent resistance between A and B is:

                           

1.  3Ω 

2.  6Ω  

3.  9Ω  

4.  12Ω

Concept Questions :-

Combination of resistors
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Current I as shown in the circuit will be

                 

1.  10 A

2.  203 A 

3.  23 A  

4.  53 A

 

Concept Questions :-

Combination of resistors
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Difficulty Level: