How can the electric potential energy stored in a charged capacitor be found from a graph of potential difference against charge?

It is equal to the area under the graph , which forms a triangle since V is directly proportional to Q .

Why is the graph of potential difference against charge for a capacitor a straight line through the origin?

Because the charge Q on a capacitor is directly proportional to its potential difference V ( C = Q / V is constant).

True or False? As a capacitor charges up, it becomes progressively easier to add more charge to the negative plate.

False. As more electrons build up on the negative plate, the electric repulsion between them increases, so progressively more work must be done to add further charge.

When calculating electric potential energy from a charge–potential difference graph, why is it important to check the units of charge and potential difference before substituting into the equation?

Charge and p.d. are often given in μC and kV ; both must be converted to C and V for the calculated energy to come out correctly in joules .

The electric potential energy stored in a capacitor is equal to the .......... under a graph of potential difference against charge.

The electric potential energy stored in a capacitor is equal to the area under a graph of potential difference against charge.

Define work done (energy stored) in charging a capacitor.

The work done , or energy stored, in charging a capacitor is equal to the area under a potential–charge ( V – Q ) graph.

True or False? The energy stored in a fully charged capacitor is given by W = QV .

False. As a capacitor charges, the potential difference across it rises from 0 to V , so the average p.d. during charging is V /2, giving W = ½QV , not QV .

The work done in charging a capacitor is equal to the .......... under a potential–charge graph.

The work done in charging a capacitor is equal to the area under a potential–charge graph.

A LevelPhysicsCambridge (CIE)Flashcards19. CapacitanceEnergy Stored in a Capacitor

Energy Stored in a Capacitor (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontArea Under a Potential–Charge Graph
How can the electric potential energy stored in a charged capacitor be found from a graph of potential difference against charge?

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Cards in this collection (12)

How can the electric potential energy stored in a charged capacitor be found from a graph of potential difference against charge?
It is equal to the area under the graph, which forms a triangle since V is directly proportional to Q.
What equation gives the electric potential energy stored by a capacitor, based on the area under a potential–charge graph?
$E P E = \frac{1}{2} Q V$
Why is the graph of potential difference against charge for a capacitor a straight line through the origin?
Because the charge Q on a capacitor is directly proportional to its potential difference V (C = Q/V is constant).
True or False?
As a capacitor charges up, it becomes progressively easier to add more charge to the negative plate.
False.
As more electrons build up on the negative plate, the electric repulsion between them increases, so progressively more work must be done to add further charge.
When calculating electric potential energy from a charge–potential difference graph, why is it important to check the units of charge and potential difference before substituting into the equation?
Charge and p.d. are often given in μC and kV; both must be converted to C and V for the calculated energy to come out correctly in joules.
The electric potential energy stored in a capacitor is equal to the .......... under a graph of potential difference against charge.
The electric potential energy stored in a capacitor is equal to the area under a graph of potential difference against charge.
Define work done (energy stored) in charging a capacitor.
The work done, or energy stored, in charging a capacitor is equal to the area under a potential–charge (V–Q) graph.
What is the equation for the work done (energy stored), W, in a capacitor in terms of charge Q and potential difference V?
$W = \frac{1}{2} Q V$
What is the equation for the work done (energy stored), W, in a capacitor in terms of capacitance C and potential difference V?
$W = \frac{1}{2} C V^{2}$
What is the equation for the work done (energy stored), W, in a capacitor in terms of charge Q and capacitance C?
$W = \frac{Q^{2}}{2 C}$
True or False?
The energy stored in a fully charged capacitor is given by W = QV.
False.
As a capacitor charges, the potential difference across it rises from 0 to V, so the average p.d. during charging is V/2, giving W = ½QV, not QV.
The work done in charging a capacitor is equal to the .......... under a potential–charge graph.
The work done in charging a capacitor is equal to the area under a potential–charge graph.

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