How do I calculate electrical energy transferred?

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Discussion Overview

The discussion revolves around calculating electrical energy transferred when given voltage and charge. It includes theoretical explanations and derivations of the relationship between energy, voltage, current, and charge.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant asks how to calculate electrical energy transferred with given voltage and charge.
  • Another participant presents the formulas for power and energy, leading to the conclusion that energy can be expressed as Energy = Voltage * Charge.
  • A participant expresses confusion about the derivation of Energy = Voltage * Charge from Energy = Voltage * Current * Time.
  • Further clarification is provided by explaining that current is defined as charge per time, allowing for the substitution in the energy equation.
  • One participant expresses understanding after the explanation.

Areas of Agreement / Disagreement

Participants generally agree on the derivation of the energy formula, but there is an initial uncertainty from one participant regarding the steps involved.

Contextual Notes

The discussion does not address potential limitations or assumptions in the formulas presented, nor does it explore any alternative methods for calculating electrical energy.

Molly1235
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Can anyone tell me how to calculate electrical energy transferred when you are given a voltage and a charge? I'm really stuck as we haven't covered this before :-/
 
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Hopefully you recognise...

Power = Voltage * Current
and
Energy = Power * Time

So

Energy = Voltage * Current * Time

but

Current * Time = Charge

(Edit: or if you prefer Current = Charge/Time)

So

Energy = Voltage * Charge
 
CWatters said:
Hopefully you recognise...

Power = Voltage * Current
and
Energy = Power * Time

So

Energy = Voltage * Current * Time

but

Current * Time = Charge

(Edit: or if you prefer Current = Charge/Time)

So

Energy = Voltage * Charge

Ok, yeah I got as far as Energy = Voltage * current * time, but I'm afraid I don't understand how you got to energy = charge * voltage? (Probably being extremely dumb here...)
 
Ok so you got as far as ...

Energy = Voltage * Current * Time ...... (eqn 1)

Think about what current is. Current is the amount of charge flowing past a point per second. Just like the current of a river is the amount of water flowing past per second.

So the definition of current is Charge/Time

Now in equation 1 above you can replace "Current" with "Charge/Time" to give

Energy = Voltage * (Charge/Time) * Time

Time cancels to leave

Energy = Voltage * Charge
 
Oooh I understand now! Thank you very much!
 

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