Capacitance Quiz: Test Your Knowledge of Electrical Storage

10th Grade

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By Thames

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Quizzes Created: 10017 | Total Attempts: 9,652,179

| Attempts: 12 | Questions: 20 | Updated: Mar 17, 2026

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1. A capacitor is a component that mainly:

Produces current by itself

Stores electric charge and energy

Creates magnetic fields only

Converts heat into light

Concept: what a capacitor does. A capacitor stores separated charge on two conductors. That stored charge also represents stored electrical energy.

Explanation

Concept: what a capacitor does. A capacitor stores separated charge on two conductors. That stored charge also represents stored electrical energy.

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About This Quiz

Capacitance Quiz: Test Your Knowledge Of Electrical Storage - Quiz

This assessment focuses on capacitance, exploring key concepts such as charge storage, dielectric materials, and circuit applications. It evaluates your understanding of how capacitors function and their significance in electrical engineering. Engaging with this material will enhance your knowledge and practical skills in handling electrical storage systems, making it essential... see morefor students and professionals alike. see less

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2. A capacitor has two terminals (plates) separated by an insulator.

True

False

Concept: capacitor structure. The insulating layer is called a dielectric. It prevents charge from flowing directly across while allowing an electric field to exist.

Explanation

Concept: capacitor structure. The insulating layer is called a dielectric. It prevents charge from flowing directly across while allowing an electric field to exist.

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3. Capacitance is defined by the relationship:

(c = ir)

(c = q/v)

(c = v/q)

(c = qv)

Concept: definition of capacitance. Capacitance measures how much charge is stored per volt of potential difference. Larger capacitance means more charge can be stored for the same voltage.

Explanation

Concept: definition of capacitance. Capacitance measures how much charge is stored per volt of potential difference. Larger capacitance means more charge can be stored for the same voltage.

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4. The SI unit of capacitance is the ______ (f).

Concept: capacitance unit. One farad means one coulomb of charge per volt. In practice, many capacitors are microfarads (µf) or nanofarads (nf).

Explanation

Concept: capacitance unit. One farad means one coulomb of charge per volt. In practice, many capacitors are microfarads (µf) or nanofarads (nf).

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5. If (c) is constant, doubling (v) doubles (q).

True

False

Concept: proportionality from (q=cv). For a fixed capacitor, charge is directly proportional to voltage. This holds as long as the capacitor behaves ideally.

Explanation

Concept: proportionality from (q=cv). For a fixed capacitor, charge is directly proportional to voltage. This holds as long as the capacitor behaves ideally.

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6. A 10 f capacitor at 5 v stores charge:

2 c

15 c

50 c

500 c

Concept: using q=cv. q=10 f×5 v=50 c. Microfarad times volt gives microcoulomb.

Explanation

Concept: using q=cv. q=10 f×5 v=50 c. Microfarad times volt gives microcoulomb.

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7. A dielectric increases capacitance compared to air/vacuum (same geometry).

True

False

Concept: dielectrics increase capacitance. A dielectric reduces the effective electric field for a given charge by polarizing. That allows more charge to be stored at the same voltage.

Explanation

Concept: dielectrics increase capacitance. A dielectric reduces the effective electric field for a given charge by polarizing. That allows more charge to be stored at the same voltage.

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8. A key practical use of a capacitor in circuits is to:

Raise gravity

Smooth voltage variations (filtering)

Make sound louder directly

Increase resistance

Concept: filtering/smoothing. Capacitors can store and release charge quickly. This helps reduce ripple in power supplies and smooth signals.

Explanation

Concept: filtering/smoothing. Capacitors can store and release charge quickly. This helps reduce ripple in power supplies and smooth signals.

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9. Capacitors can charge and discharge over time in a circuit.

True

False

Concept: time behavior. Charge does not appear instantly because current must flow to move charge onto plates. The circuit’s resistance affects how fast this happens.

Explanation

Concept: time behavior. Charge does not appear instantly because current must flow to move charge onto plates. The circuit’s resistance affects how fast this happens.

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10. During charging from a battery, the capacitor’s voltage:

Starts at the battery voltage immediately

Starts at 0 and rises toward the battery voltage

Starts above the battery voltage

Stays at 0 forever

Concept: charging trend. At first the capacitor is uncharged, so voltage is 0. As charge builds, capacitor voltage increases until it approaches the supply voltage.

Explanation

Concept: charging trend. At first the capacitor is uncharged, so voltage is 0. As charge builds, capacitor voltage increases until it approaches the supply voltage.

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11. When a capacitor is fully charged in a DC circuit (steady state), the current through it is approximately zero.

True

False

Concept: DC steady-state behavior. Once the capacitor voltage matches the supply, charge flow stops. In ideal circuits it behaves like an open circuit for DC after charging.

Explanation

Concept: DC steady-state behavior. Once the capacitor voltage matches the supply, charge flow stops. In ideal circuits it behaves like an open circuit for DC after charging.

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12. Capacitors block steady DC after charging but can allow changing current (AC) because they can and .

Concept: capacitors and changing signals. With AC or changing voltages, the capacitor repeatedly charges and discharges. That creates current even though the dielectric blocks direct conduction.

Explanation

Concept: capacitors and changing signals. With AC or changing voltages, the capacitor repeatedly charges and discharges. That creates current even though the dielectric blocks direct conduction.

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13. Which pair of units matches (q), (v), and (c) correctly?

(q) in volts, (v) in coulombs, (c) in ohms

(q) in coulombs, (v) in volts, (c) in farads

(q) in amps, (v) in joules, (c) in watts

(q) in farads, (v) in ohms, (c) in coulombs

Concept: correct units. Charge is coulombs, voltage is volts, capacitance is farads. These match the defining equation (c=q/v).

Explanation

Concept: correct units. Charge is coulombs, voltage is volts, capacitance is farads. These match the defining equation (c=q/v).

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14. A larger capacitance means more charge stored for the same voltage.

True

False

Concept: interpreting capacitance. From (q=cv), increasing (c) increases (q) for fixed (v). That’s why large capacitors can store more charge.

Explanation

Concept: interpreting capacitance. From (q=cv), increasing (c) increases (q) for fixed (v). That’s why large capacitors can store more charge.

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15. If you increase the separation between capacitor plates (same area and dielectric), the capacitance generally:

Increases

Decreases

Stays the same

Becomes infinite

Concept: geometry effect (qualitative). Bigger separation weakens the electric field coupling and reduces capacitance. Closer plates store more charge per volt.

Explanation

Concept: geometry effect (qualitative). Bigger separation weakens the electric field coupling and reduces capacitance. Closer plates store more charge per volt.

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16. A capacitor can store energy in its electric field.

True

False

Concept: energy storage mechanism. Work is done to separate charges against attraction. That work is stored as electric potential energy in the field between plates.

Explanation

Concept: energy storage mechanism. Work is done to separate charges against attraction. That work is stored as electric potential energy in the field between plates.

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17. A capacitor rated '16 v' means you should not exceed about ______ volts across it in normal use.

Concept: voltage rating and breakdown. Exceeding the rated voltage can break down the dielectric. That can cause failure or dangerous heating.

Explanation

Concept: voltage rating and breakdown. Exceeding the rated voltage can break down the dielectric. That can cause failure or dangerous heating.

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18. A camera flash uses a capacitor mainly because it can:

Produce electricity from nothing

Release stored energy quickly to make a bright flash

Lower the speed of light

Increase mass

Concept: rapid energy release. Capacitors can discharge quickly through a lamp circuit. This provides a large burst of power for a short time.

Explanation

Concept: rapid energy release. Capacitors can discharge quickly through a lamp circuit. This provides a large burst of power for a short time.

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19. Real capacitors can leak a small current through the dielectric over time.

True

False

Concept: non-ideal behavior. Real dielectrics are not perfect insulators. Leakage slowly reduces stored charge if the capacitor is left disconnected.

Explanation

Concept: non-ideal behavior. Real dielectrics are not perfect insulators. Leakage slowly reduces stored charge if the capacitor is left disconnected.

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20. The best overall summary is:

Capacitance is resistance to current

Capacitance measures charge stored per volt ((c=q/v)); capacitors store energy in an electric field and charge/discharge in circuits

Capacitors only work with AC

Dielectrics reduce capacitance

Concept: capacitance recap. Capacitance links charge and voltage and explains energy storage. Circuit behavior comes from how capacitors charge and discharge over time.

Explanation

Concept: capacitance recap. Capacitance links charge and voltage and explains energy storage. Circuit behavior comes from how capacitors charge and discharge over time.

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