EASY
AS and A Level
IMPORTANT
Earn 100

Calculate the average current required to charge a $50 \mu \mathrm{F}$ capacitor to a potential difference of $10 \mathrm{~V}$ in a time interval of $0.01 \mathrm{~s}$

Important Questions on Capacitance

MEDIUM
AS and A Level
IMPORTANT

A student connects an uncharged capacitor of capacitance C In series with a resistor, a cell and a switch. The student closes the switch and records the current I At intervals of 10s. The results are shown in table. The potential difference across the capacitor after 60s was 8.5V. Plot a current–time graph, and use it to estimate the value of C.

t /s 0 10 20 30 40 50 60
1 / µA 200 142 102 75 51 37 27

 

EASY
AS and A Level
IMPORTANT

State the quantity represented by the gradient of the straight line shown in Figure.

Question Image

The area under a graph of voltage against charge gives a quantity of energy. The area in figure a shows the energy stored in a capacitor; the area in figure b shows the energy required to drive a charge through a resistor.

EASY
AS and A Level
IMPORTANT

The graph of Figure shows how V Depends on Q For a particular capacitor.

Question Image

The energy stored by a capacitor is equal to the area under the graph of voltage against charge.

The area under the graph has been divided into strips to make it easy to calculate the energy stored. The first strip (which is simply a triangle) shows the energy stored when the capacitor is charged up to 10V. The energy stored is 12QV=12×1.0 mC×1.0 V=0.5 mJ. Calculate the capacitance C Of the capacitor.

EASY
AS and A Level
IMPORTANT

Calculate the total capacitance of two 100μF capacitors connected in parallel.

EASY
AS and A Level
IMPORTANT
Calculate the total charge that total capacitance of two 100μF capacitors connected in parallel.store when charged to a p.d. of 20 V.
EASY
AS and A Level
IMPORTANT
A capacitor of capacitance 50μF is required, but the only values available to you are 10μF,20μF and 100μF (you may use more than one of each value). How would you achieve the required value by connecting capacitors in parallel? Give at least two answers.
EASY
AS and A Level
IMPORTANT
Calculate the total capacitance of three capacitors of capacitances 200μF,300μF and 600μF, connected in series.
EASY
AS and A Level
IMPORTANT

You have a number of identical capacitors, each of capacitance C. Determine the total capacitance when:

 Two capacitors are connected in series.