Calculate Power Wasted in Cell: Help with EMF & Resistance

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Discussion Overview

The discussion revolves around calculating the power wasted in a cell with a given electromotive force (emf) and internal resistance when connected to an external resistor. It involves concepts of electrical power, internal resistance, and circuit analysis.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant presents a scenario involving a cell with an emf of 1.5V and an internal resistance of 0.5 ohms connected to a 2.5 ohm resistor, calculating the current and terminal potential difference.
  • The same participant expresses confusion about how to calculate the power wasted in the cell using the equation relating total power supplied, power delivered to the resistor, and power wasted.
  • Another participant hints at determining the power dissipated in the internal resistance of the battery as a way to find the wasted power.
  • A subsequent reply confirms that finding the power delivered to the internal resistance will yield the wasted power.

Areas of Agreement / Disagreement

Participants generally agree on the approach to find the power wasted in the cell by calculating the power dissipated in the internal resistance. However, the initial participant's confusion about the calculations indicates some uncertainty remains.

Contextual Notes

The discussion does not resolve the specific mathematical steps or assumptions involved in the calculations, leaving them open for further clarification.

Who May Find This Useful

This discussion may be useful for students or individuals learning about electrical circuits, power calculations, and the effects of internal resistance in batteries.

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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 I am 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 :)
 
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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:
ahh.. so i jus find out the amount of power delivered to the internal resistor and then that's my wasted power?
 
Yes, that's right.

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

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