Power - time rate of doing work or expending energy

P = W/t

(watts)

(J/seconds)

since V = W/q,

CROSS MULTIPLY

then W = Vq

P = Vq/t

P = VI

(All equations in reference table)

P = VI since V = IR …

THEN P = I^{2}R

since I = V/R …

THEN P = V^{2}/R

P = VI = I^{2}R = V^{2}/R

P = W/t

Giancoli p. 516) 11

a) R = 20. ohms

P = W/t = VI

W = VIt

= 12V[.60 A]60 sec

b) 430 J

Ex) A series circuit contains two lamps
and a battery with a potential difference of 1.5 volts.
If the current in the circuit is
0.10 ampere, at what rate does the circuit use energy?

Ex) Series circuit w/ two lamps, the battery
supplies a potential difference of 1.5 volts.
Current in the circuit is
0.10 ampere, what
rate does the circuit use energy?