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Current Electricity - ISC Class 12 Physics Questions with Answers, Page 3

103 past-paper questions on Current Electricity from ISC Class 12 Physics papers (2027-2018), newest first, in full. Questions 41-60 are on this page, 20 to a page. Tap "Show answer" under a question to see its answer.

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2025 · 3 marks · Short answerOpen: The drift velocity of electrons in a conductor connected to a battery is given…

Solve the following.

The drift velocity of electrons in a conductor connected to a battery is given by $v_d = -eE\tau/m$. Here, $e$ is the charge of the electron, $E$ is the electric field, $\tau$ is the average time between collisions and $m$ is the mass of the electron. Based on this, answer the following:
(a)[1.5]
How does the drift velocity change with a change in the potential difference across the conductor?
(b)[1.5]
A copper wire of length '$l$' is connected to a source. If the copper wire is replaced by another copper wire of the same area of cross-section but of length '$4l$', how will the drift velocity change? Explain your answer.

No answer yet.

2025 · 2 marks · Short answerOpen: Figures 4 and 5 represent the combination of two identical cells having…

Answer the following.

Figures 4 and 5 represent the combination of two identical cells having negligible internal resistance.
Figure for this question
(a)[1.0]
In which of the two combinations, emf of the battery is greater?
(b)[1.0]
When a resistor ‘$R$’ is connected between the terminals P and Q, $I_1$ and $I_2$ are the currents flowing through ‘$R$’ in Figure 4 and Figure 5 respectively. Obtain the ratio $\frac{I_1}{I_2}$.

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2025 · 1 mark · Short answerOpen: Using a cell of electromotive force (e.m.f.) and internal resistance 'r', a…

Answer the following.

Using a cell of electromotive force (e.m.f.) $\varepsilon$ and internal resistance 'r', a student designs an electrical circuit to calculate current 'I' through a variable resistor 'R'. The student plots her findings on a graph as shown. What does the slope of the graph indicate?

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2025 · 1 mark · DrawingOpen: Current I flowing through a metallic wire is gradually increased. Show…

Draw the following.

Current I flowing through a metallic wire is gradually increased. Show graphically how heating power (P) developed in it varies with the current (I).

Draw: graph of heating power (P) versus current (I)

Must show: P on vertical axis, I on horizontal axis, parabolic curve passing through origin

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2024 · 3 marks · NumericalOpen: Figure 2 below shows two batteries and having emfs of and and internal…

Solve the following.

Figure 2 below shows two batteries $E_1$ and $E_2$ having emfs of $18\text{ V}$ and $10\text{ V}$ and internal resistances of $1\,\Omega$ and $2\,\Omega$ respectively. $W_1$, $W_2$ and $W_3$ are uniform metallic wires AC, FD and BE having resistance of $8\,\Omega$, $6\,\Omega$ and $10\,\Omega$ respectively. B and E are midpoints of the wires $W_1$ and $W_2$. Using Kirchhoff’s laws of electrical circuits, calculate the current flowing in the wire $W_3$.
Figure for this question

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2024 · 1 mark · MCQOpen: A metre bridge is balanced with a known resistance (R) in the left hand gap and…

Choose the correct option.

A metre bridge is balanced with a known resistance (R) in the left hand gap and an unknown resistance (S) in the right hand gap. Balance point is found to be at a distance of $l\text{ cm}$ from the left hand side. When the battery and the galvanometer are interchanged, balance point will
  • (a)shift towards left.
  • (b)shift towards right.
  • (c)remain same.
  • (d)shift towards left or right depending on the values of R and S.

No answer yet.

2024 · 3 marks · NumericalOpen: Figure 3 below shows a potentiometer circuit in which the driver cell D has an…

Solve the following.

Figure 3 below shows a potentiometer circuit in which the driver cell D has an emf of $6\text{ V}$ and internal resistance of $2\,\Omega$. The potentiometer wire AB is $10\text{ m}$ long and has a resistance of $28\,\Omega$. The series resistance $R_s$ is of $20\,\Omega$. Calculate:
Figure for this question
(a)[1.5]
The current $I_p$ flowing in the potentiometer wire AB when the jockey (J) does not touch the wire AB.
(b)[1.5]
Emf of the cell X if the balancing length AC is $4.5\text{ m}$.

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2023 · 3 marks · NumericalOpen: In the circuit shown in Figure 3 below, and are batteries having emfs of and …

Solve the following.

In the circuit shown in Figure 3 below, $E_1$ and $E_2$ are batteries having emfs of $25\text{ V}$ and $26\text{ V}$. They have an internal resistance of $1\,\Omega$ and $5\,\Omega$ respectively. Applying Kirchhoff’s laws of electrical networks, calculate the currents $I_1$ and $I_2$.
Figure 3
Figure 3

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