# Electric Circuits Homework Help

1. Jan 19, 2010

### r1ch412d

I dont have much of a homework problem that i need help with, but the homework requires us to use a equation ...

P = E / t

there is a little triangle before the E
i don't know what it means

Thanks for help

Last edited: Jan 19, 2010
2. Jan 20, 2010

### Yitzach

$$P=\frac{\Delta E}{t}$$
I can tell you what the $$\Delta$$ (capital delta) and the t mean but I can't be sure what the equation is all about unless I know that E or P is.
$$\Delta$$ means "change in." As in change in the variable between two points, generally time or space. In this case between two points in time as you have a per t.
I have seen P mean momentum, power, point, polarization, and dipole moment. I have seen E mean energy and electric field. Only two of these makes sense together in this equation.
I think P is power measured in watts, E is energy measured in joules, and t is time measured in seconds. It would read "Power is equal to the change in energy per unit time." For this version to work, you need to know the objects energy at two points in time, find their difference, and then divide by the time between the two points in time.
I will see this equation as either:
$$P=\frac{\Delta E}{\Delta t}=\frac{dE}{dt}$$