In Class 12 Boards there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Downloads of CBSE Class 12 Physics Chapter 2 Electrostatic Potential and Capacitance Case Study and Passage-Based Questions with Answers were Prepared Based on the Latest Exam Pattern. Students can solve NCERT Class 12 Physics Case Study Questions Electrostatic Potential and Capacitance to know their preparation level.
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In CBSE Class 12 Physics Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
Electrostatic Potential and Capacitance Case Study Questions With Answers
Here, we have provided case-based/passage-based questions for Class 12 Physics Chapter 2 Electrostatic Potential and Capacitance
Case Study/Passage-Based Questions
Case Study 1: A dielectric slab is a substance that does not allow the flow of charges through it but permits them to exert electrostatic forces on one another.
When a dielectric slab is placed between the plates, the field Eo polarises the dielectric. This induces charge -Qp on the upper surface and + Qp on the lower surface of the dielectric. These induced charges set up a field Ep inside the dielectric in the opposite direction of E⃗ 0E→0 as shown.
(I) In a parallel plate capacitor, the capacitance increases from 4μF to 80μF on introducing a dielectric medium between the plates. What is the dielectric constant of the medium?
| (a) 10 | (b) 20 | (c) 50 | (d) 100 |
Answer: (b) 20
(ii) A parallel plate capacitor with air between the plates has a capacitance of 8 pF. The separation between the plates is now reduced by half and the space between them is filled with a medium of dielectric constant 5.
Calculate the value of capacitance of the capacitor in the second case.
| (a) 8pF | (b) 10pF | (c) 80pF | (d) 100pF |
Answer: (c) 80pF
(iii) A dielectric introduced between the plates of a parallel plate condenser
| (a) decreases the electric field between the plates | (b) increases the capacity of the condenser |
| (c) increases the charge stored in the condenser | (d) increases the capacity of the condenser |
Answer: (d) increases the capacity of the condenser
(iv) A parallel plate capacitor of capacitance 1 pF has separation between the plates is d. When the distance of separation becomes 2d and wax of dielectric constant x is inserted in it the capacitance becomes 2 pF. What is the value of x?
| (a) 2 | (b) 4 | (c) 6 | (d) 8 |
Answer: (b) 4
Case Study 2:When an insulator is placed in an external field, the dipoles become aligned. Induced surface charges on the insulator establish a polarization field Ēi in its interior. The net field Ē in the insulator is the vector sum of Ē, and Ēi as shown in the figure.
In the application of an external electric field, the effect of aligning the electric dipoles in the insulator is called polarization, and the field Ē; is known as the polarisation field.
The dipole moment per unit volume of the dielectric is known as polarisation (P).
For linear isotropic dielectrics, P =χE, where χ = electrical susceptibility of the dielectric medium.
(i) Which among the following is an example of a polar molecule?
(2) O₂
(b) H
(c) N2
(d) HCI
Answer: (d) HCI
(ii) When air is replaced by a dielectric medium of constant K, the maximum force of attraction between two charges separated by a distance
(a) increases K times
(b) remains unchanged
(c) decreases K times
(d) increases 2K times.
Answer: (c) decreases K times
(iii) Which of the following is a dielectric?
(a) Copper
(b) Glass
(c) Antimony (Sb)
(d) None of these
Answer: (c) Antimony (Sb)
(iv) For a polar molecule, which of the following statements is true ?
(a) The centre of gravity of electrons and protons coincide.
(b) The centre of gravity of electrons and protons do not coincide.
(c) The charge distribution is always symmetrical.
(d) The dipole moment is always zero.
Answer: (b) The centre of gravity of electrons and protons do not coincide.
(v) When a comb rubbed with dry hair attracts pieces of paper. This is because the
(a) comb polarizes the piece of paper
(b) comb induces a net dipole moment opposite to the direction of field
(c) electric field due to the comb is uniform
(d) comb induces a net dipole moment perpendicular to the direction of field
Answer: (a) comb polarizes the piece of paper
Case Study 3: Electrostatic Potential and Capacitance, explores the concepts of electric potential energy, electric potential, and capacitance. The electric potential at a point in an electric field is the amount of work done per unit charge in bringing a positive test charge from infinity to that point against the electric force. It’s important to note that the potential energy of a system of charges is defined as the work done in assembling the system of charges from infinity. The chapter further introduces the concept of capacitance. A capacitor is a device that stores electrical energy in an electric field. It’s essentially a system of two conductors separated by an insulator, and its capacitance is the ratio of the amount of charge stored on one conductor to the potential difference between the conductors.
What is the electric potential at a point in an electric field?
A) The amount of work done per unit charge in bringing a negative test charge from infinity to that point.
B) The amount of work done per unit charge in bringing a positive test charge from infinity to that point.
C) The force experienced by a unit positive charge at that point.
D) The force experienced by a unit negative charge at that point.
How is the potential energy of a system of charges defined?
A) As the work done in disassembling the system of charges to infinity.
B) As the work done in assembling the system of charges from infinity.
C) As the force experienced by the system of charges.
D) As the amount of charge in the system.
What is a capacitor?
A) A device that measures the potential difference between two points.
B) A device that measures the amount of charge in an electric field.
C) A device that stores electrical energy in an electric field.
D) A device that converts electrical energy into mechanical energy.
What is the capacitance of a capacitor?
A) The ratio of the potential difference between the conductors to the amount of charge stored on one conductor.
B) The ratio of the amount of charge stored on one conductor to the potential difference between the conductors.
C) The total amount of charge stored on the conductors.
D) The potential difference between the conductors.
What does a capacitor essentially consist of?
A) Two conductors separated by an insulator.
B) Two insulators separated by a conductor.
C) A single conductor surrounded by an insulator.
D) A single insulator surrounded by a conductor.
Answers:
- B) The amount of work done per unit charge in bringing a positive test charge from infinity to that point.
- B) As the work done in assembling the system of charges from infinity.
- C) A device that stores electrical energy in an electric field.
- B) The ratio of the amount of charge stored on one conductor to the potential difference between the conductors.
- A) Two conductors separated by an insulator.
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