Electrostatics, as one of the foundational topics in physics, delves into the phenomena that arise from charges that are at rest. When these charges move, they produce an electric current. But what about when they’re stationary? This is where the concepts of electrostatic potential and capacitance come into play. These concepts are crucial to understanding many modern-day applications, from simple capacitors in electronic circuits to advanced technologies in energy storage. In this blog post, we present a series of MCQs to test your understanding of these essential topics. Let’s dive in!
1. What is the potential energy of two charges separated by distance r in vacuum?
Answer:
Explanation:
The potential energy (U) of two point charges q1 and q2 separated by a distance r in vacuum is described by the formula U = (k q1 q2) / r.
2. A capacitor has a capacitance of 5μF. If its capacitance becomes 10μF upon inserting a dielectric, what is the dielectric constant of the material?
Answer:
Explanation:
The dielectric constant k is the ratio of the capacitance with the dielectric to the capacitance without the dielectric. Hence, k = 10μF/5μF = 2.
3. What does the electrostatic potential due to a point charge depend upon?
Answer:
Explanation:
Electrostatic potential depends on all the given factors.
4. Capacitors are devices that can store __________.
Answer:
Explanation:
Capacitors store energy in the form of an electric field between their plates.
5. Which of the following is not a unit of capacitance?
Answer:
Explanation:
Ohm is a unit of resistance, not capacitance.
6. If the distance between plates of a capacitor is halved and the area is doubled, the capacitance will:
Answer:
Explanation:
Capacitance is directly proportional to the area of the plates and inversely proportional to the distance between them.
7. An electric dipole consists of charges of:
Answer:
Explanation:
An electric dipole consists of two charges of equal magnitude but opposite sign separated by some distance.
8. What will be the potential at a point due to a charge Q?
Answer:
Explanation:
The potential at a point due to a charge is inversely proportional to the distance from the charge.
9. The ability of a capacitor to store charge for a given potential difference is termed as:
Answer:
Explanation:
Capacitance defines the ability of a capacitor to store charge for a given potential difference.
10. A dielectric material is inserted between the plates of a capacitor. What will happen to its capacitance?
Answer:
Explanation:
The introduction of a dielectric increases the capacitance because it reduces the effective electric field between the plates.
11. Electrostatic potential is a ___________ quantity.
Answer:
Explanation:
Electrostatic potential is a scalar quantity as it has only magnitude without direction.
12. Electrostatic potential energy of a system increases if:
Answer:
Explanation:
When work is done against the electrostatic force, energy is stored in the system as electrostatic potential energy.
13. In a parallel plate capacitor with air between the plates, when the distance between the plates is doubled, the capacitance:
Answer:
Explanation:
Capacitance is inversely proportional to the distance between the plates.
14. The unit Farad can also be represented as:
Answer:
Explanation:
Capacitance is defined as the ratio of the charge (Q) stored on a conductor to the potential (V) across it. Therefore, F = C/V. Rearranging, we get the unit of capacitance (Farad) as C^2/J.