Equations Unit 8

Question 1

Coulomb’s Law

Answer 1

The force of polar attraction = (9e9 q1q2) / r^2

Question 2

Strength of an electric field

Answer 2

9e9|q| / r^2

Question 3

Potential Energy of 2 point charges

Answer 3

(9e9 q1q2) / r

Question 4

Potential energy of an electric field

Answer 4

q * strength of the electric field * distance between the charge and the negative plate

Question 5

Electric potential (voltage)

Answer 5

Potential energy / q or, in terms of work:
w / q

Question 6

Voltage of a single charge

Answer 6

kq / r

Question 7

Voltage of an electric field

Answer 7

Ed

Question 8

Capacitance (farads)

Answer 8

C = Q / V

Question 9

|| plate capacitor (F)

Answer 9

8.85e-12 * (area of plates / distance between the plates)

Question 10

Potential energy of a capacitor

Answer 10

1/2 * capacitance * voltage^2

Question 11

Current

Answer 11

Change in charge / change in time

Question 12

Ohm’s law

Answer 12

Current = Current * resistance

Question 13

Junction rule

Answer 13

The total current entering a junction is equal to the total current leaving the junction
I1 = I2 + I3

Question 14

Second law (loop rule)

Answer 14

The voltage drops in a closed circuit must add up to zero

Question 15

Power (watts)

Answer 15

Current^2 * Resistance or
Voltage^2 / Resistance