What is the average drift speed of conduction electrons in a copper wire of cross-sectional area 1.0×10-7 m2 carrying a current of 1.5 A? Assume that each copper atom contributes roughly one conduction electron. The density of copper is 9.0×103 kg/m3, and its atomic mass is 63.5 u. 

1. 1.1 mm s-1
2.  2.1 mm s-1
3.  3.1 mm s-1
4.  4.1 mm s-1

Subtopic:  Current & Current Density |
 55%
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An electric toaster uses nichrome for its heating element. When a negligibly small current passes through it, its resistance at room temperature (27.0 °C) is found to be 75.3 . When the toaster is connected to a 230 V supply, the current settles, after a few seconds, to a steady value of 2.68 A. What is the steady temperature of the nichrome element? The temperature coefficient of resistance of nichrome averaged over the temperature range involved is 1.70 × 10–4 °C–1

1. 8270 C
2. 8200 C
3. 8470 C
4. 8000 C

Subtopic:  Heating Effects of Current |
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The resistance of the platinum wire of a platinum resistance thermometer at the ice point is 5  and at the steam point is 5.23 . When the thermometer is inserted into a hot bath, the resistance of the platinum wire is 5.795 . The temperature of the bath is:

1. 300.200C
2. 345.650C
3. 320.200C
4. 400.120C

Subtopic:  Heating Effects of Current |
 64%
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A network of resistors is connected to a 16 V battery with an internal resistance of 1Ω, as shown in the figure. The equivalent resistance of the network is:

     

1. 4Ω
2. 5Ω
3. 7Ω
4. 2Ω

Subtopic:  Combination of Resistors |
 81%
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A network of resistors is connected to a 16 V battery with an internal resistance of 1 Ω, as shown in the figure. The current in 1 Ω resistor between B and C will be:

1. 4 A
2. 2 A
3. 1 A
4. 3 A

Subtopic:  Combination of Resistors |
 84%
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A network of resistors is connected to a 16 V battery with an internal resistance of 1 Ω, as shown in the figure. The voltage drop across AB is:

1. 2 V

2. 25 V

3. 4 V

4. 6 V

Subtopic:  EMF & Terminal Voltage |
 77%
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A battery of 10 V and negligible internal resistance is connected across the diagonally opposite corners of a cubical network consisting of 12 resistors each of resistance 1 Ω (as shown in the figure). The total current in the network is:

       

1. 6 A
2. 12 A
3. 4 A
4. 2 A

Subtopic:  Kirchoff's Voltage Law |
 65%
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The current in the branch AB in the given network is:

 
1. 5/8 A

2. 5/2 A

3. 15/8 A

4. 3/2 A

Subtopic:  Kirchoff's Voltage Law |
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The four arms of a Wheatstone bridge have the following resistances as shown in the figure. A galvanometer of 15 resistance is connected across BD. What is the current through the galvanometer when a potential difference of 10 V is maintained across AC?

     

1. 4.87 mA

2. 3.72 mA

3. 5.01 mA

4. 2.65 mA

Subtopic:  Wheatstone Bridge |
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In a meter bridge (shown in the figure), the null point is found at a distance of 33.7 cm from A. If now a resistance of 12 Ω is connected in parallel with S, the null point occurs at 51.9 cm. The values of R and S are respectively:

1. 13.5 Ω, 6.86 Ω
2.  13.5 Ω, 13.5 Ω
3.  6.86 Ω, 6.86 Ω
4.  6.86 Ω, 13.5 Ω

Subtopic:  Meter Bridge & Potentiometer |
 52%
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