Capacitance and Capacitors

A simple capacitor of capacitance C is produced using 2 parallel plates of area A and separation d. (Air is used as the dielectric material). If the separation of the plates is halved to d/2 and the area of both plates is doubled, the new capacitance will be:

• C

• 2 C

• 4 C

• 8 C

Tags

NGSS.HS-PS3-2

Capacitors are made using 'dielectric materials'. Which of these statements best describes a dielectric material?

• A conductor that can be polarised

• A conductor that cannot be polarised

• An insulator that can be polarised

• An insulator that cannot be polarised

Tags

NGSS.HS-PS3-5

A 10^-4 F capacitor is connected to a 10 V cell. What is the charge and energy stored on the capacitor?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-5

Two large capacitors of value 1 F and 2 F are wired in series and then in parallel. What is the total capacitance when combined like this?

• A

• B

• C

• D

Identical capacitors are connected in different combinations. Which of these capacitor networks has the largest capacitance?

• A

• B

• C

• D

Which of the following graphs best shows the potential difference across a capacitor charging through a resistor?

• A

• B

• C

• D

The energy stored in a capacitor is E when charged to a voltage V₀. After a time τ the potential difference across the capacitor has fallen to 0.69 V₀ as it discharges through a resistor. This means that the energy transferred to the resistor in this time will be:

• 0.31 E

• 0.69² E

• (1 - 0.69²) E

• 0.31² E

Tags

NGSS.HS-PS3-2

A capacitor discharges through a fixed resistor. The time constant τ for the capacitor and resistor is 10 seconds. At what time will the charge across the capacitor have dropped to half the original value?

• 0.5 e^-10

• 10 e^-0.5

• 10 ln(-0.5)

• -10 ln(0.5)

Tags

NGSS.HS-PS3-5

A capacitor X of capacitance C is charged by connecting it, with a movable lead, to a battery of emf E.

The lead is moved so that capacitor X is first disconnected from the battery and then connected to a second capacitor Y of capacitance C.

What is the energy stored in capacitor Y?

• 1/8 CE²

• 1/4 CE²

• 1/2 CE²

• CE²

Tags

NGSS.HS-PS3-5

Two plates hold identical and opposite electric charges, +Q and -Q, and are separated by a distance d. What is the electric potential at the mid-point between these two plates?

• 2Q

• Q / d

• 2Q / d

• zero

Tags

NGSS.HS-PS2-4