electricity - shocking!

Question 1

potential energy of charges

Answer 1

PE=-qEdeltaX

PE= QV

Why does this work?

Well, E= V/x, so in essence

PE=qV/x*x or simply

PE=qV

Note also that qE=F (electric force equals charge times electric field, the go between equation) SO really the first equation is no more than force*distance (work)

Question 2

Voltage

Answer 2

kq/r

charge per distance

V=Q/Capacitance

Joules/coulomb

Work per charge

To increase voltage means to increase the amount of work that each charge can do.

Also, V=electric field * distance

kq/d^2*d= kq/d

Question 3

Does it take energy to move a charge along an equipotential line? why or why not?

Answer 3

PE = QdeltaV

If the voltage doesn’t change, then no work is done

Question 4

Capacitors

Answer 4

C=Q/V

coulomb/volt

charge per (charge per distance or work per charge)

epsilonA/d

Question 5

Explain why a dielectric increases the maximum operating voltage of a capacitor even though the physical size of the capacitor doesn’t change.

Answer 5

The material of the dielectric may be able to withstand a larger electric field than air can withstand before breaking down to pass a spark between the capacitor plates.

Question 6

When a dielectric is introduced, does the voltage go up or down?

Answer 6

Down

Being said, the battery’s voltage does not change. Does this mean that the voltage between the plates can actually be greater than the battery?

Question 7

What is the potential energy of a capacitor?

Answer 7

PE=1/2QV

Question 8

When you add a dielectric, what do you do??

Answer 8

C=KCnaught

C=KepsilonA/d

You can increase capacitance by increasing area, decreasing distance.

C=Q/V

You can also increase capacitance by decreasing the voltage (like using a dielectric).

Question 9

When you are wondering about capacitance and electric fields and the possibility that the dielectric might break down, what do you remember?

Answer 9

C=Q/V

and V=electric field times distance

Often you’re not going to be given the voltage, but you’ll prob be given a distance and a max field strength before breakdown. There ya go.

Question 10

capacitors in series

Answer 10

capacitance is the product/sum

charges same

I=I1=I2=I3=…

voltages add

V=V1+V2+V3+…

Question 11

capacitors in parallel

Answer 11

capacitance simply adds

charges simply add

voltage is the same

Question 12

resistors in series

Answer 12

resistance simply adds

current same

voltage adds

Question 13

resistors in parallel

Answer 13

resistance is product/sum

different current

same voltage

Question 14

power?

Answer 14

P=IV

Question 15

plate of charges

Answer 15

E=Q/2epsilonA

parallel plate

E=Q/epsilonA

bc the positive negative plates reinforce each other