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#1 Class Class 12 Physics Current Electricity 2022 Short 5M

(i) Derive an expression for drift velocity of free electrons.
(ii) How does drift velocity vary with increase in temperature? Explain.

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#2 Class Class 12 Physics Current Electricity 2023 Short 5M

Define current density $J$ of a metallic conductor. Deduce the relation connecting $J$ and conductivity $\sigma$ when electric field $E$ is applied.

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#3 Class Class 12 Physics Current Electricity 2022 Short 3M

A wire of uniform cross-section and resistance 4 $\Omega$ is bent into a square ABCD. Point A is connected to point P on DC by a wire AP of resistance 1 $\Omega$. When potential difference is applied between A and C, points B and P are at same potential. Find resistance of part DP.

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#4 Class Class 12 Physics Current Electricity 2019 Short 3M

A heating element using nichrome connected to a 230 V supply draws initial current of 3.2 A which settles to 2.8 A. Find steady temperature if room temperature is 27°C. ($\alpha_{nichrome} = 1.70 \times 10^{-4}$ °C$^{-1}$)

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#5 Class Class 12 Physics Current Electricity 2021 Short 3M

A wire of uniform cross-section and resistance 12 $\Omega$ is bent in the shape of a circle. A resistance of 10 $\Omega$ is connected to diametrically opposite ends C and D. A battery of emf 8 V is connected between A and B. Determine the current flowing through arm AD.

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#6 Class Class 12 Physics Current Electricity 2022 Short 5M

Using Kirchhoff's laws, obtain the equation for the balanced state in a Wheatstone bridge.

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#7 Class Class 12 Physics Current Electricity 2023 Short 3M

A heating element connected across a battery of 100 V having internal resistance 1 $\Omega$ draws initial current of 10 A at 20°C. What is the power consumed by battery itself after steady temperature of 320°C? ($\alpha = 3.70 \times 10^{-4}$ °C$^{-1}$)

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#8 Class Class 12 Physics Current Electricity 2022 Long 5M

Write two limitations of Ohm's law. Sketch their $I$-$V$ characteristics.

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#9 Class Class 12 Physics Current Electricity 2023 Long 5M

(I) Currents $I_1$, $I_2$, $I_3$ at a junction satisfy $I_1 = I_2 + I_3$.
(A) State the fundamental law from which this is derived.
(B) Explain how Kirchhoff's Voltage Law validates conservation of energy.
(II) How does the balancing condition of a Wheatstone bridge get affected if galvanometer and cell are interchanged?

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#10 Class Class 12 Physics Current Electricity 2017 Short 2M

Find the relation between internal resistance $r$, emf $E$, external resistance $R$, and the total current $I$ in the circuit.

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#11 Class Class 12 Physics Current Electricity 2020 Short 2M

The graph shows potential difference $V$ across terminals of a cell against load current $I$. How do you find emf and internal resistance from this graph?

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#12 Class Class 12 Physics Current Electricity 2022 Short 5M

Define current density and relaxation time. Derive an expression for resistivity of a conductor in terms of number density of charge carriers $n$ and relaxation time $\tau$.

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#13 Class Class 12 Physics Current Electricity 2021 Short 2M

Define mobility of a charge carrier. What is its relation with relaxation time?

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#14 Class Class 12 Physics Current Electricity 2019 Short 2M

What do you mean by sensitivity of a Wheatstone bridge? On what factors does it depend?

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#15 Class Class 12 Physics Current Electricity 2018 Short 1M

Define the current sensitivity of a galvanometer. Write its SI unit.

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#16 Class Class 12 Physics Current Electricity 2020 Short 2M

The emf of a cell is always greater than its terminal voltage. Why? Give reason.

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#17 Class Class 12 Physics Current Electricity 2019 Short 2M

Nichrome and Copper wires of same length and same radius are connected in series. Current $I$ is passed through them. Which wire gets heated up more? Justify your answer.

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#18 Class Class 12 Physics Current Electricity 2018 Short 1M

Write the expression for the drift velocity of charge carriers in a conductor of length $L$ across which a potential difference $V$ is applied.

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#19 Class Class 12 Physics Current Electricity 2022 Short 3M

A coil contains $N$ turns of insulated copper wire of diameter $d$ and resistivity $\rho$ wound on a cylinder of diameter $D$. What is the total resistance between the two ends of the coil? (Given: $D \gg d$)

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#20 Class Class 12 Physics Current Electricity 2019 Short 2M

Internal resistance of a cell of emf 12 V is 0.05 $\Omega$. Find the voltage across the cell when a current of 60 A is drawn from it.

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