6.1, 6.2 (capacitors and gravitational fields)

Capacitor

stores energy by separating charges via plates causing one to be positively charged and the other negatively charged

How do capacitors work?

• when connected to an emf the charge can not cross the plates

• when disconnected from the emf the electrons move from the negative plate to the positive plate

• once all electrons have moved to the positive plate the capacitor is discharged

How do you find the total capacitance in a parallel circuit?

• CT = C1 + C2 + C3 …

How do you find the total capacitance in a series curcuit?

1/CT = 1/C1 + 1/C2 ….

What is the equation for charging a capacitor?

Q = Q0 (1- e^-t/CR)

same for voltage

I = I0e^-t/CR

What direction do electric field lines go?

positive to negative

What does Coulomb’s law state?

the electric force between two point charges is:

• directly proportional to the product of their charges

• inversely proportional to the square of their separation

Electric potential

the work done per unit positive charge to mover from infinity (where potential is zero) to a point in the electric field

Define the Farad

Coulomb per unit voltage