EASY
12th CBSE
IMPORTANT
Earn 100

A carbon filament has a resistance of 100 Ω at 0°C. What must be the resistance of a copper filament placed in series with carbon so that the combination has the same resistance at all temperatures? Temperature coefficient of resistance of carbon=0.0007C1 and that of copper is 0.004°C1.

Important Questions on Current Electricity

EASY
12th CBSE
IMPORTANT
Calculate the temperature at which the resistance of a conductor becomes 20% more than that its resistance at 27°C. The value of the temperature coefficient of resistance of the conductor is 2.0×104/K.
EASY
12th CBSE
IMPORTANT
The current through a conductor is 1 ampere when the temperature is 0° C and 0.7 ampere when the temperature is 100° C. What would be current when the temperature of the conductor is 1200° C?
EASY
12th CBSE
IMPORTANT
The lengths and radii of three wires of same metal are in the ratios 2 : 3 : 4 and 3 : 4 : 5 respectively. They are joined in parallel and included in a circuit having 5 A current. Find current in each wire.
EASY
12th CBSE
IMPORTANT

Five 4Ω resistances, a 2V battery and an ammeter are connected as shown in . Find, the ammeter reading.

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MEDIUM
12th CBSE
IMPORTANT

Calculate the steady-state current through 2Ω resistor in the circuit shown in Fig. The internal resistance of the battery is negligible and C=2μF

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MEDIUM
12th CBSE
IMPORTANT

As shown in Fig., a variable rheostat of 2  is used to control the potential difference across a 500 Ω load.

If the resistance AB is 500 Ω, what is the potential difference across the load?

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MEDIUM
12th CBSE
IMPORTANT

As shown in Fig., a variable rheostat of 2  is used to control the potential difference across a 500 Ω load.

If the load is removed, what should be the resistance at BC to get 40 V between B and C ?

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MEDIUM
12th CBSE
IMPORTANT

In the circuit shown in Fig., both the ammeter and the cell have negligible resistance. Three external resistors are identical. When the switch S is opened, the ammeter reads 0.6 A. What will the ammeter read when the switch S is closed?

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