EASY
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Find the potential difference across the 700 Ω resistance, i.e., V0 for the following circuit.

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Important Questions on Current Electricity

EASY

I-V characteristic of a copper wire of length L and area of cross-section A is shown in figure. The slope of the curve becomes

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HARD
A voltmeter having a resistance of 900 Ω is used to measure the potential difference across a 100 Ω resistor which is connected to a battery of emf 150 V and internal resistance 10 Ω. The percentage of decrease in the potential difference across the 100 Ω resistor when the voltmeter is connected across it is
HARD

As shown in the schematic below, a rod of uniform cross-sectional area A and length l is carrying a constant current i through it and voltage across the rod is measured using an ideal voltmeter. The rod is stretched by the application of a force F.

Which of the following graphs would show the variation in the voltage across the rod as function of the strain ε when the strain is small. Neglect Joule heating.

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MEDIUM
A cylindrical wire of radius 0.5 mm and conductivity 5×107 S m-1 is subjected to an electric field of 10 mV m-1. The expected value of current in the wire will be x3π mA. The value of x is _________.
MEDIUM
To verify Ohm’s law, a student connects the voltmeter across the battery as shown in the figure. The measured voltage is plotted as a function of the current, and the following graph is obtained:
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If Vo is almost zero, identify the correct statement:
EASY

I - V graphs for two different electrical appliances P and Q are shown in the diagram. If RP and RQ be the resistances of the devices, then

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EASY

An ideal ammeter is connected to a battery as shown in the figure. The currents through the 5.0 Ω resistor and the 2.0 Ω resistor are, respectively

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MEDIUM

Find the voltage and current passing through the resistor R2 shown in the following circuit

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EASY
When a diode is forward biased, it has a voltage drop of 0.5 V . the safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode so that the current does not exceed the safe limit is :
EASY
A circuit to verify Ohm's law uses ammeter and voltmeter in series or parallel connected corrected correctly to the resistor. In the circuit :
EASY

What is the current in the 4 Ω resistor when switch S1 is open and switch S2 is closed in the given circuit?

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EASY

In the circuit shown below, a student performing Ohm's law experiment accidentally puts the voltmeter and the ammeter as shown in the circuit below; the reading in the voltmeter will be close to
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HARD

For the circuit shown, the value of current at time t=3.2 s will be ______ A.

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[Voltage distribution V(t) is shown by Fig. (1) and the circuit is shown in Fig. (2)]

MEDIUM
In the circuit shown, the cells A and B have negligible resistances for VA=12 V, R1=500 Ω and R=100 Ω. The galvanometer G shows no deflection. The value of VB is

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EASY
Current flowing through a circuit is shown in the figure then the resistance of the circuit is
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EASY

The current through the 36 Ω resistor in the given circuit is

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EASY

Find the potential difference between a and b, as shown in the below circuit.

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EASY

In the figure shown, what is the current (in ampere) drawn from the battery? You are given:
R1=15 Ω , R2=10 Ω , R3=20 Ω , R4=5 Ω, R5=25 Ω, R6=30 Ω, E=15 V
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MEDIUM
The resistivity of potentiometer wire is 40×10-8 Ω m and its area of cross-section is 8×10-6 m2. If 0.2 A current is flowing through the wire, the potential gradient of the wire is