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Current Electricity - ISC Class 12 Physics Questions with Answers, Page 5

103 past-paper questions on Current Electricity from ISC Class 12 Physics papers (2027-2018), newest first, in full. Questions 81-100 are on this page, 20 to a page. Tap "Show answer" under a question to see its answer.

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2022 · 1 mark · MCQOpen: A 2 volt battery, a resistor and a potentiometer of 100 cm length, all are…

Choose the correct option.

A 2 volt battery, a $15\ \Omega$ resistor and a potentiometer of 100 cm length, all are connected in series. If the resistance of potentiometer wire is $5\ \Omega$, then the potential gradient of the potentiometer wire is…
  • (a)$0.005\text{ V/cm}$
  • (b)$0.05\text{ V/cm}$
  • (c)$0.02\text{ V/cm}$
  • (d)$0.2\text{ V/cm}$

No answer yet.

2022 · 3 marks · Case basedOpen: Two bulbs B1 and B2 are connected in series with an source of emf 250V as shown…

Study the information given and answer the questions that follow.

Two bulbs B1 and B2 are connected in series with an source of emf 250V as shown in the figure 15 below. The labels on the bulbs read 250V, 80W and 250V, 100W respectively.
Figure for this question
(i)[1.0]
What will be the ratio of the resistance of the bulbs R1/R2?
  • (a)5 : 4
  • (b)4 : 5
  • (c)1 : 1
  • (d)5 : 3
(ii)[1.0]
What will be the ratio of the power consumed (P1/P2) when connected in series?
  • (a)5 : 4
  • (b)4 : 5
  • (c)1 : 1
  • (d)5 : 3
(iii)[1.0]
What is the ratio of the pd across the bulbs (V1/V2)?
  • (a)5 : 4
  • (b)4 : 5
  • (c)1 : 1
  • (d)5 : 3

No answer yet.

2022 · 1 mark · MCQOpen: If m, e, and n respectively represent the mass, charge, average relaxation time…

Choose the correct option.

If m, e, $\tau$ and n respectively represent the mass, charge, average relaxation time and density of the electron, then what will be the resistance of a wire of length l and area of cross-section A?
  • (a)$\frac{ml}{n e^2 \tau A}$
  • (b)$\frac{m A}{n e^2 \tau^2 l}$
  • (c)$\frac{n e^2 \tau A}{2 ml}$
  • (d)$\frac{n e^2 \tau A}{ml}$

No answer yet.

2022 · 3 marks · Case basedOpen: Given below is a neat, labelled diagram to obtain balancing condition of…

Study the information given and answer the questions that follow.

Given below is a neat, labelled diagram to obtain balancing condition of Wheatstone bridge.
Figure for this question
(i)[1.0]
Why is the key ‘K’ pressed before the key K1?
  • (a)There is no such requirement
  • (b)To avoid a back emf in the closed loops
  • (c)There is no current till the key ‘K’ is pressed
  • (d)None of these
(ii)[1.0]
What is the relation between the potential at ‘B’ and ‘D’, when the bridge is balanced?
  • (a)$V_B > V_D$
  • (b)$V_B < V_D$
  • (c)$V_B = V_D$
  • (d)$V_B \ge V_D$
(iii)[1.0]
What is the galvanometer current when the bridge is balanced?
  • (a)Ig flows from ‘B’ to ‘D’
  • (b)Ig flows from ‘D to ‘B’
  • (c)Ig has no significance in this case
  • (d)$I_g = 0$

No answer yet.

2020 · 3 marks · NumericalOpen: and are two batteries having emfs of and and internal resistances of and…

Solve the following.

$E_1$ and $E_2$ are two batteries having emfs of $3\text{V}$ and $4\text{V}$ and internal resistances of $2\ \Omega$ and $1\ \Omega$ respectively. They are connected as shown in Figure 2 below. Using Kirchhoff’s Laws of electrical circuits, calculate the currents $I_1$ and $I_2$.
Figure for this question

No answer yet.

2020 · 3 marks · NumericalOpen: A potentiometer circuit is shown in Figure 3 below. AB is a uniform metallic…

Solve the following.

A potentiometer circuit is shown in Figure 3 below. AB is a uniform metallic wire having length of $2\text{ m}$ and resistance of $8\ \Omega$. The batteries $E_1$ and $E_2$ have emfs of $4\text{ V}$ and $1\cdot5\text{ V}$ and their internal resistances are $1\ \Omega$ and $2\ \Omega$ respectively.
Figure for this question
(i)[2.0]
When the jockey J does not touch the wire AB, calculate: (a) the current flowing through the potentiometer wire AB. (b) the potential gradient across the wire AB.
(ii)[1.0]
Now the jockey J is made to touch the wire AB at a point C such that the galvanometer (G) shows no deflection. Calculate the length AC.

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2019 · 3 marks · DrawingOpen: Draw a labelled circuit diagram of a potentiometer to measure the internal…

Derive the following.

Draw a labelled circuit diagram of a potentiometer to measure the internal resistance ‘r’ of a cell. Write the working formula (derivation is not required).

Draw: Circuit diagram of a potentiometer to measure internal resistance of a cell

Must show: Potentiometer wire, Driving cell / accumulator, Rheostat, Key, Test cell with internal resistance r, Resistance box, Galvanometer, Jockey

No answer yet.

2018 · 3 marks · NumericalOpen: and are two batteries having emf of and respectively and internal resistance of…

Solve the following.

$\varepsilon_1$ and $\varepsilon_2$ are two batteries having emf of $34\text{V}$ and $10\text{V}$ respectively and internal resistance of $1\,\Omega$ and $2\,\Omega$ respectively. They are connected as shown in Figure 3 below. Using Kirchhoff’s Laws of electrical networks, calculate the currents $I_1$ and $I_2$.
Figure for this question

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