# physics-energy

how do i calculate the total energy transferred over a period of time?
thanks!
here's the question
Youve been given information that lets you calculate power (current and Volts)

You hopefully remember (or could work out for yourself) that power multiplied by time gives you energy...maybe helpful to remember the electric company sends out energy bills with consumption measured in kWh (kilo Watt hours)
High level: Summation of average energy for each period

E = (0.2x1.6x1 + 0.188x1.5x2 + 0.163x1.3x3 + 0.145x1.15x1 + 0.83x0.65x1) x 3600

This is what has been given in the markscheme. I used energy=current*voltage*time. But i dont know where the values 0.188, 0.163,0.145,0.83 have been obtained and 1.5,1.3 etc?
Thanks!
I think they'll have graphed it and be taking the area under the line by trapeziums.
Original post by Ashirs
High level: Summation of average energy for each period

E = (0.2x1.6x1 + 0.188x1.5x2 + 0.163x1.3x3 + 0.145x1.15x1 + 0.83x0.65x1) x 3600

This is what has been given in the markscheme. I used energy=current*voltage*time. But i dont know where the values 0.188, 0.163,0.145,0.83 have been obtained and 1.5,1.3 etc?
Thanks!

0.188, 0.163, 0.145, 0.83 are the "average current" or the "midpoint current value" during the time interval.

(200 + 175) / 2 = 187.5 mA 0.188 A
(175 + 150) / 2 = 162.5 mA 0.163 A
etc

In fact, it is what Joinedup has mentioned in post #5.
Original post by Eimmanuel
0.188, 0.163, 0.145, 0.83 are the "average current" or the "midpoint current value" during the time interval.

(200 + 175) / 2 = 187.5 mA 0.188 A
(175 + 150) / 2 = 162.5 mA 0.163 A
etc

In fact, it is what Joinedup has mentioned in post #5.

ohhh, ok thank you!