HARD
JEE Main/Advance
IMPORTANT
Earn 100

Find the final charges in steady state on the four capacitors of capacitance 2μF, 4μF, 6μF and 8μF as shown in figure. (Assuming initially they are uncharged). Also find the current through the wire AB at steady state.

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Important Questions on Current Electricity

HARD
JEE Main/Advance
IMPORTANT

A capacitor is connected to a 12 V battery through a resistance of 10Ω. It is found that the potential difference across the capacitor rises to 4.0 V in 1μs. Find the capacitance of the capacitor.

(Given : ln3 = 1.0986, ln2 = 0.693)

 

HARD
JEE Main/Advance
IMPORTANT

A capacitor of capacity 1μF is connected in a closed series circuit with a resistance of 107 ohms, an open key and a cell of 2 V with negligible internal resistance:

i When the key is switched on at time t = 0, find;

a The time constant for the circuit.

(b) The charge on the capacitor at steady state.

(c) Time taken to deposit charge equal to half of charge that will deposit at steady state.

(ii) If after completely charging the capacitor, the cell is shorted by zero resistance at time t = 0, find the charge on the capacitor at t = 50 s. (Given : e5 = 6.73×103 , ln2 = 0.693)

HARD
JEE Main/Advance
IMPORTANT

A 5.0 μ F capacitor having a charge of 20 μ C is discharged through a wire of resistance 5.0 Ω. Find the heat dissipated in the wire between 25 to 50 μs after the connections are made. (Given : e2 = 0.135)

 

HARD
JEE Main/Advance
IMPORTANT

A varying voltage is applied to the clamps AB (figure a) such that the voltage across the capacitor plates varies as shown in figure b.

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Plot the time dependence of voltage across the clamps CD.

 

HARD
JEE Main/Advance
IMPORTANT

A capacitor of capacitance C is charged by charge q0. At t = 0, it is connected to a battery of emf V and internal resistance r. Find the charge on the capacitor at time t (positive plate of capacitor connected with positive plate of battery).

 

MEDIUM
JEE Main/Advance
IMPORTANT

In the circuit shown find

(a) the power drawn from the cell,

(b) the power consumed by the resistor which is converted into heat and

(c) the power given to the inductor.

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MEDIUM
JEE Main/Advance
IMPORTANT
Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area 1.0×107 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 amu.
EASY
JEE Main/Advance
IMPORTANT

A current of 5 A exists in a 10 Ω resistance for 4 minutes.

i How many coulombs and

ii How many electrons pass through any cross-section of the resistor at this time? Charge of the electron=1.6×10-19 C.