An electric capacitor, commonly known as a capacitor, is a passive electrical component that stores energy in an electric field. It consists of two conductive plates separated by an insulating material called a dielectric. When a voltage is applied across the plates, one accumulates positive charge and the other negative charge, allowing the capacitor to hold energy until discharged.
Capacitors are fundamental in electronics for functions like energy storage, filtering noise in power supplies, timing circuits, and signal processing. They vary in types, including:
Ceramic capacitors: Compact and used in high-frequency applications due to their stability.
Electrolytic capacitors: Offer high capacitance for bulk energy storage, often in power supplies.
Film capacitors: Known for precision and reliability in audio and industrial circuits.
Supercapacitors: Provide very high capacitance for rapid energy discharge in applications like electric vehicles.
The key property is capacitance, measured in farads (F), which indicates how much charge the capacitor can store per unit voltage. The basic formula is C = Q/V, where C is capacitance, Q is charge, and V is voltage. Capacitors play a crucial role in modern devices, from smartphones to electric grids, by managing electrical flow and stability.
Table of contents
- Part 1: Best AI quiz making software for creating a electric capacitor quiz
- Part 2: 20 electric capacitor quiz questions & answers
- Part 3: OnlineExamMaker AI Question Generator: Generate questions for any topic
Part 1: Best AI quiz making software for creating a electric capacitor quiz
Nowadays more and more people create electric capacitor quizzes using AI technologies, OnlineExamMaker a powerful AI-based quiz making tool that can save you time and efforts. The software makes it simple to design and launch interactive quizzes, assessments, and surveys. With the Question Editor, you can create multiple-choice, open-ended, matching, sequencing and many other types of questions for your tests, exams and inventories. You are allowed to enhance quizzes with multimedia elements like images, audio, and video to make them more interactive and visually appealing.
Take a product tour of OnlineExamMaker:
● Create a question pool through the question bank and specify how many questions you want to be randomly selected among these questions.
● Build and store questions in a centralized portal, tagged by categories and keywords for easy reuse and organization.
● Simply copy a few lines of codes, and add them to a web page, you can present your online quiz in your website, blog, or landing page.
● Randomize questions or change the order of questions to ensure exam takers don’t get the same set of questions each time.
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Part 2: 20 electric capacitor quiz questions & answers
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1. Question: What is the unit of capacitance?
Options:
A. Ohm
B. Volt
C. Farad
D. Ampere
Answer: C. Farad
Explanation: Capacitance is defined as the ability of a capacitor to store charge per unit voltage, and its SI unit is the farad (F), which is equivalent to coulombs per volt.
2. Question: In a capacitor, the electric field is stored in which medium?
Options:
A. The dielectric material
B. The conductive plates
C. The wires connecting the plates
D. The surrounding air
Answer: A. The dielectric material
Explanation: The electric field in a capacitor is primarily stored in the dielectric material between the plates, which helps in increasing the capacitance by reducing the electric field strength.
3. Question: What happens to the capacitance of a parallel-plate capacitor if the distance between the plates is doubled?
Options:
A. It doubles
B. It halves
C. It remains the same
D. It quadruples
Answer: B. It halves
Explanation: Capacitance is inversely proportional to the distance between the plates (C = εA/d), so if the distance doubles, the capacitance decreases by half.
4. Question: Which factor does NOT affect the capacitance of a capacitor?
Options:
A. Area of the plates
B. Distance between the plates
C. Material of the plates
D. Dielectric constant of the material between plates
Answer: C. Material of the plates
Explanation: The capacitance depends on the plate area, distance between plates, and the dielectric constant, but not on the material of the plates themselves, as long as they are good conductors.
5. Question: What is the energy stored in a capacitor given by?
Options:
A. QV/2
B. QV
C. CV^2
D. Both A and C
Answer: D. Both A and C
Explanation: The energy stored in a capacitor is given by U = (1/2)QV or U = (1/2)CV^2, where Q is charge, V is voltage, and C is capacitance.
6. Question: In a series connection of capacitors, how is the equivalent capacitance calculated?
Options:
A. Sum of individual capacitances
B. Product of individual capacitances divided by their sum
C. Reciprocal of the sum of reciprocals
D. Average of individual capacitances
Answer: C. Reciprocal of the sum of reciprocals
Explanation: For capacitors in series, the equivalent capacitance C_eq is given by 1/C_eq = 1/C1 + 1/C2 + …, meaning it’s less than the smallest individual capacitance.
7. Question: What is the charge on a capacitor when it is fully charged?
Options:
A. Zero
B. Equal to the capacitance
C. Q = CV
D. Infinite
Answer: C. Q = CV
Explanation: The charge on a capacitor is related to the voltage across it by Q = CV, where C is capacitance and V is the applied voltage.
8. Question: How does inserting a dielectric material affect the capacitance of a capacitor?
Options:
A. Decreases it
B. Increases it
C. Has no effect
D. Depends on the voltage
Answer: B. Increases it
Explanation: A dielectric material increases the capacitance by reducing the effective electric field between the plates, allowing more charge to be stored for the same voltage.
9. Question: What is the time constant for an RC circuit?
Options:
A. R + C
B. RC
C. 1/(RC)
D. R/C
Answer: B. RC
Explanation: The time constant τ in an RC circuit is the product of resistance R and capacitance C, representing the time it takes for the capacitor to charge or discharge to about 63% of its maximum value.
10. Question: In a parallel connection of capacitors, what is the equivalent capacitance?
Options:
A. Sum of individual capacitances
B. Reciprocal of the sum of reciprocals
C. Product divided by sum
D. Smallest capacitance
Answer: A. Sum of individual capacitances
Explanation: For capacitors in parallel, the equivalent capacitance is the algebraic sum of the individual capacitances, as the total charge is the sum of charges on each capacitor.
11. Question: What happens to the voltage across capacitors in a series connection?
Options:
A. It is the same for each
B. It adds up to the total voltage
C. It is zero
D. It depends on the charge
Answer: B. It adds up to the total voltage
Explanation: In series, the charge on each capacitor is the same, but the voltages across them add up to the total applied voltage.
12. Question: Which type of capacitor has a fixed capacitance?
Options:
A. Electrolytic capacitor
B. Variable capacitor
C. Ceramic capacitor
D. Both A and C
Answer: D. Both A and C
Explanation: Electrolytic and ceramic capacitors typically have fixed capacitance values, unlike variable capacitors which can be adjusted.
13. Question: What is the formula for the capacitance of a spherical capacitor?
Options:
A. C = 4πε₀r
B. C = ε₀A/d
C. C = 4πε₀ (r1 r2)/(r2 – r1)
D. C = ε₀/r
Answer: C. C = 4πε₀ (r1 r2)/(r2 – r1)
Explanation: For a spherical capacitor with inner radius r1 and outer radius r2, the capacitance is given by C = 4πε₀ (r1 r2)/(r2 – r1).
14. Question: During the discharging of a capacitor in an RC circuit, the current is:
Options:
A. Constant
B. Exponential decay
C. Exponential growth
D. Zero
Answer: B. Exponential decay
Explanation: The current during discharging follows an exponential decay pattern, given by I = I0 e^(-t/τ), where τ is the time constant.
15. Question: What is the effect of increasing the area of the plates in a capacitor?
Options:
A. Decreases capacitance
B. Increases capacitance
C. No change
D. Depends on the dielectric
Answer: B. Increases capacitance
Explanation: Capacitance is directly proportional to the plate area (C = εA/d), so a larger area allows more charge storage for the same voltage.
16. Question: In which scenario is the energy stored in a capacitor maximum?
Options:
A. When fully discharged
B. When half-charged
C. When fully charged
D. When voltage is zero
Answer: C. When fully charged
Explanation: The energy stored is U = (1/2)CV^2, which is maximum when the capacitor is fully charged and at its rated voltage.
17. Question: What is the dielectric constant?
Options:
A. Ratio of capacitance with dielectric to capacitance without
B. Resistance of the dielectric
C. Voltage across the capacitor
D. Charge on the plates
Answer: A. Ratio of capacitance with dielectric to capacitance without
Explanation: The dielectric constant κ is defined as the factor by which the capacitance increases when a dielectric material is inserted between the plates.
18. Question: For two identical capacitors, how should they be connected to get the maximum capacitance?
Options:
A. In series
B. In parallel
C. Either way
D. Not possible
Answer: B. In parallel
Explanation: Connecting capacitors in parallel adds their capacitances directly, resulting in a higher equivalent capacitance than in series.
19. Question: What is the voltage-current relationship in a capacitor?
Options:
A. I = C dV/dt
B. V = IR
C. V = Q/C
D. Both A and C
Answer: D. Both A and C
Explanation: The relationship is given by I = C dV/dt (for changing voltage) and V = Q/C (for steady state), describing how capacitors behave in circuits.
20. Question: Why do capacitors block DC current?
Options:
A. They have infinite resistance to DC
B. Once charged, no current flows through them
C. They store energy indefinitely
D. DC voltage is too high
Answer: B. Once charged, no current flows through them
Explanation: In a DC circuit, a capacitor charges up to the supply voltage and then acts as an open circuit, blocking further steady DC current flow.
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