Capacitance is the charge stored per unit potential .

Why are capacitance values usually quoted in microfarads (μF), nanofarads (nF) or picofarads (pF) rather than farads?

Because one farad (1 C V -1 ) is a very large unit in practice, so real capacitors have much smaller capacitances.

A dielectric is the material between the plates of a capacitor that ensures charge does not flow freely between the plates.

True or False? A charged capacitor stores a net charge on the capacitor itself.

False. Each plate stores an equal and opposite charge, so the net charge on the capacitor as a whole is zero; the charge is stored on the plates, not by the capacitor itself.

The capacitance of an isolated spherical conductor is given by C = .......... , where R is the radius of the sphere.

The capacitance of an isolated spherical conductor is given by C = 4πε₀R , where R is the radius of the sphere.

Why can the charge on the surface of a charged spherical conductor be treated as a point charge at its centre when finding its potential?

The charge distributes evenly over the conducting surface, so it behaves mathematically as if it were a single point charge located at the sphere's centre.

In a series arrangement of capacitors, what quantity is the same on each capacitor, and what quantity is shared between them?

The charge Q is the same on each capacitor; the total potential difference V is shared between them ( V = V 1 + V 2 + ...)

In a parallel arrangement of capacitors, what quantity is the same across each capacitor, and what quantity is shared between them?

The potential difference V is the same across each capacitor; the total charge Q is shared between them ( Q = Q 1 + Q 2 + ...)

True or False? The equations for combining capacitors in series and parallel are the same as the equations for combining resistors in series and parallel.

False. They are the opposite way round : capacitors in series combine like resistors in parallel (reciprocal sum), and capacitors in parallel combine like resistors in series (direct sum)

Why does the charge Q cancel out when deriving the combined capacitance equation for capacitors in series ?

Because the current is the same through all components in a series circuit, so the charge on each capacitor is the same, allowing Q to cancel from both sides of the equation.

Why does the potential difference V cancel out when deriving the combined capacitance equation for capacitors in parallel ?

Because the potential difference is the same across every branch in a parallel circuit, allowing V to cancel from both sides of the equation.

For two identical capacitors connected in series , how does the combined capacitance compare to each individual capacitance?

The combined capacitance is equal to half the value of each individual capacitor.

For two identical capacitors connected in parallel , how does the combined capacitance compare to each individual capacitance?

The combined capacitance is equal to twice the value of each individual capacitor.

True or False? The combined capacitance of capacitors connected in series is always greater than the individual capacitances.

False. The combined capacitance in series is always less than the value of the smallest individual capacitance.

How does the combined capacitance of capacitors connected in parallel compare with each individual capacitance in that arrangement?

The combined capacitance in parallel is always greater than any individual capacitance in the arrangement.

For capacitors connected in series, the reciprocal of the combined capacitance is equal to the .......... of the reciprocals of the individual capacitances.

For capacitors connected in series, the reciprocal of the combined capacitance is equal to the sum of the reciprocals of the individual capacitances.

A LevelPhysicsCambridge (CIE)Flashcards19. CapacitanceCapacitors & Capacitance

Capacitors & Capacitance (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontCapacitance
Define capacitance.

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Cards in this collection (20)

Define capacitance.
Capacitance is the charge stored per unit potential.
What equation relates capacitance, charge and potential difference?
$C = \frac{Q}{V}$
Why are capacitance values usually quoted in microfarads (μF), nanofarads (nF) or picofarads (pF) rather than farads?
Because one farad (1 C V^-1) is a very large unit in practice, so real capacitors have much smaller capacitances.
Define dielectric.
A dielectric is the material between the plates of a capacitor that ensures charge does not flow freely between the plates.
True or False?
A charged capacitor stores a net charge on the capacitor itself.
False.
Each plate stores an equal and opposite charge, so the net charge on the capacitor as a whole is zero; the charge is stored on the plates, not by the capacitor itself.
The capacitance of an isolated spherical conductor is given by C = .........., where R is the radius of the sphere.
The capacitance of an isolated spherical conductor is given by C = 4πε₀R, where R is the radius of the sphere.
Why can the charge on the surface of a charged spherical conductor be treated as a point charge at its centre when finding its potential?
The charge distributes evenly over the conducting surface, so it behaves mathematically as if it were a single point charge located at the sphere's centre.
In a series arrangement of capacitors, what quantity is the same on each capacitor, and what quantity is shared between them?
The charge Q is the same on each capacitor; the total potential difference V is shared between them (V = V₁ + V₂ + ...)
In a parallel arrangement of capacitors, what quantity is the same across each capacitor, and what quantity is shared between them?
The potential difference V is the same across each capacitor; the total charge Q is shared between them (Q = Q₁ + Q₂ + ...)
For capacitors connected in series, the combined capacitance is given by $\frac{1}{C_{t o t a l}} =$ ..........
For capacitors connected in series, the combined capacitance is given by $\frac{1}{C_{t o t a l}} = \frac{1}{C_{1}} + \frac{1}{C_{2}} + \frac{1}{C_{3}} . . .$
What is the equation for the combined capacitance of capacitors connected in parallel?
$C_{t o t a l} = C_{1} + C_{2} + C_{3} . . .$
True or False?
The equations for combining capacitors in series and parallel are the same as the equations for combining resistors in series and parallel.
False.
They are the opposite way round: capacitors in series combine like resistors in parallel (reciprocal sum), and capacitors in parallel combine like resistors in series (direct sum)
Why does the charge Q cancel out when deriving the combined capacitance equation for capacitors in series?
Because the current is the same through all components in a series circuit, so the charge on each capacitor is the same, allowing Q to cancel from both sides of the equation.
Why does the potential difference V cancel out when deriving the combined capacitance equation for capacitors in parallel?
Because the potential difference is the same across every branch in a parallel circuit, allowing V to cancel from both sides of the equation.
For two identical capacitors connected in series, how does the combined capacitance compare to each individual capacitance?
The combined capacitance is equal to half the value of each individual capacitor.
For two identical capacitors connected in parallel, how does the combined capacitance compare to each individual capacitance?
The combined capacitance is equal to twice the value of each individual capacitor.
True or False?
The combined capacitance of capacitors connected in series is always greater than the individual capacitances.
False.
The combined capacitance in series is always less than the value of the smallest individual capacitance.
How does the combined capacitance of capacitors connected in parallel compare with each individual capacitance in that arrangement?
The combined capacitance in parallel is always greater than any individual capacitance in the arrangement.
A network contains capacitors connected in parallel, with the result then connected in series to a further capacitor. What is the correct order of steps to find the total capacitance?
- First combine the parallel branch using $C_{t o t a l} = C_{1} + C_{2} + . . .$
- Then combine this result in series with the remaining capacitor using $\frac{1}{C_{t o t a l}} = \frac{1}{C_{1}} + \frac{1}{C_{2}} . . .$
For capacitors connected in series, the reciprocal of the combined capacitance is equal to the .......... of the reciprocals of the individual capacitances.
For capacitors connected in series, the reciprocal of the combined capacitance is equal to the sum of the reciprocals of the individual capacitances.

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