Capacitors

Capacitors

Be ready to explore

Multiple Select

What are the factors that influence capacitance of a capacitor?

• Surface area

• Temperature

• Dielectric

• Length

• Distance between plates

Multiple Choice

What is the unit of C?

• Farad

• No unit

• Coulomb

• Volt

Multiple Choice

The capacity of parallel plate condenser depends on

• The type of metal used

• The thickness of plates

• The potential applied across the plates

• The separation between the plates

Multiple Choice

During charging a capacitor variation of potential V of the capacitor with time t is shown as

Multiple Choice

When a slab of dielectric material is introduced between the parallel plates of a capacitor which remains connected to a battery, then charge on plates relative to earlier charge

• Is less

• Is same

• Is more

• May be less or more depending on the nature of the material introduced

Cylindrical Capacitor

Electric field in this case is given by:
E= $\frac{Q}{2\pi r\epsilon_o}$ 

Derivation

• Finding V by  $V=\int_{ }^{ }E.dr$  

• using the value of potential difference in C=Q/V

Spherical Capacitor

Electric field in this case is given by:
E= $\frac{Q}{4\pi r^2\epsilon_o}$  

Combination of capacitors

Two possible combinations: Series And Parallel

Series Combinations of capacitors

• all capacitors of a series combination have the same charge. (This occurs due to the conservation of charge in the circuit.)

• But, V1=Q/C1,V2=Q/C2, and V3=Q/C3

  
  

Parallel Combination of capacitors

• All have the same voltage V across their plates. 

• Q=Q1+Q2+Q3

  
  

Multiple Choice

What is the ratio of

 $\frac{V_1}{V_2}$  

•  $1$  

•  $\frac{C_1}{C_2}$  

•  $\frac{C_2}{C_1}$  

•  $\frac{C_1+C_2}{C_1C_2}$  

Open Ended

A student has a 20μF capacitor, a 47μF capacitor, and a 82μF capacitor.

What is the largest capacitance that she can make from the three capacitor in μF.

Multiple Choice

The resultant capacitance between and in the following figure is equal to

• 1 $\mu$ F

• 3 $\mu$ F

• 2 $\mu$ F

• 1.5 $\mu$ F

Multiple Choice

Three equal capacitors, each with capacitance are connected as shown in figure. Then the equivalent capacitance between and is

• C

• C/3

• 3C

• 3C/2

Multiple Choice

A 5uF, a 10uF and a 20uF capacitor are connected in PARALLEL to a 6V battery. Calculate the total equivalent capacitance of the circuit?

• 35uF

• 0,35uF

• 2,857uF

• 0,0286uF

Multiple Choice

A 5uF, a 10uF and a 20uF capacitor are connected in PARALLEL to a 6V battery. Calculate the total equivalent capacitance of the circuit?

• 35uF

• 0,35uF

• 2,857uF

• 0,0286uF