A 12V, 40 A hr battery is connected to a 15 Watt lamp. How long will the battery last??
2007-02-11 05:49:11 · 6 answers · asked by dancer131 1 in Science & Mathematics ➔ Physics
if you use the battery non-stop
2007-02-11 06:34:49 · update #1
32 hours, assuming that there is no resistance in the circuit and no internal resistance in the battery. It's a fairly simple equation: 12V * 40 A hr = 480 Watt hours of energy in the battery (work = voltage*current*time). Divide 480 by the 15 watts required to run the lamp and you get 32 hours (all of the units cancel).
Of course in reality, some energy would be lost to heat due to resistance in the circuitry and inside the battery, so the actual duration of light produced would be less than 32 hours.
2007-02-11 07:44:27 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Assuming the 15 W lamp is intended for 12V:
15 W = E*I = 12*I
I = 15/12 amps = 1.25 amps
40 A*hr / 1.25 amps = 32 hours
2007-02-11 07:56:48 · answer #2 · answered by sojsail 7 · 0⤊ 0⤋
12v 5ah Battery
2016-10-18 10:39:22 · answer #3 · answered by Anonymous · 0⤊ 0⤋
about 4 to 5 hours
2007-02-11 05:54:16 · answer #4 · answered by dil man 1 · 0⤊ 4⤋
Depends how long your using it!
2007-02-11 05:52:28 · answer #5 · answered by avant1991 3 · 0⤊ 1⤋
till their power finish
2007-02-11 05:55:19 · answer #6 · answered by strangegal 1 · 0⤊ 3⤋