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Help with power?

  • Thread starter ad_astra
  • Start date
  • #1
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a cell of emf 1.5V and internal resistance 0.5 ohms is connected to a 2.5 ohm resistor.

ive calculated the current as 0.5A
terminal pd as 1.25V
and calculated the power delivered to the 2.5 ohm resistor.

now i have to calculate the power wasted in the cell?

ive got the equation Ie = I^2 + I^2r
which is the power supplied by the cell = the power delivered to R + the power wasted in the cell.

but im so confused. on rearranging it and subsituting the numbers in?

can anyone shed any light on how i do this? and if so can you give me the equation and talk me through it please..

thanks :)
 

Answers and Replies

  • #2
vk6kro
Science Advisor
4,081
40
Hint:
How much power is dissipated in the internal resistance of the battery?

A battery can only generate power but a resistor can "waste" it.
 
Last edited:
  • #3
2
0
ahh.. so i jus find out the amount of power delivered to the internal resistor and then thats my wasted power?
 
  • #4
vk6kro
Science Advisor
4,081
40
Yes, that's right.

Asking it like that just turned a simple problem into a difficult one.
 

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