Why Use e.m.f. Instead of Terminal Voltage for Power Calculation?

In summary, The conversation discusses the calculation of power transformed by battery B using different methods. One method involves using the terminal voltage of the battery, while the other involves using the e.m.f. of the battery. The difference in results may be due to the definition of "power transformed" and how it is calculated.
  • #1
Janiceleong26
276
4
1. Homework Statement
image.jpg

image.jpg

Homework Equations


P=IV

The Attempt at a Solution


I used the terminal voltage of battery B, that is I minus the voltage across the internal resistance of battery B from the e.m.f. of battery B, then I multiply it with the current which is 2.5A (calculated earlier) . But it should be just the e.m.f. of battery B multiply the current. Why the e.m.f. and not the terminal p.d.?
 
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  • #2
That's probably a matter of definition of "power transformed by battery B". One calculation gives the power that actually leaves the battery, one gives the power that is required from the energy source within the battery (a part of it will heat the battery).
 
  • #3
mfb said:
That's probably a matter of definition of "power transformed by battery B". One calculation gives the power that actually leaves the battery, one gives the power that is required from the energy source within the battery (a part of it will heat the battery).
Got it, thanks
 

Related to Why Use e.m.f. Instead of Terminal Voltage for Power Calculation?

What is a battery's power transformation?

A battery's power transformation is the conversion of chemical energy into electrical energy. This occurs when the battery undergoes a chemical reaction, producing a flow of electrons that can be harnessed to power devices.

How does a battery transform power?

A battery transforms power through a series of chemical reactions that occur between its positive and negative terminals. These reactions generate an electrical current, which can then be used to power devices.

What factors affect a battery's power transformation?

There are several factors that can affect a battery's power transformation, including the type of battery, its size and capacity, the materials used in its construction, and the conditions in which it is used (such as temperature and humidity).

What happens when a battery's power is drained?

When a battery's power is drained, it means that it no longer has enough chemical energy to produce an electrical current. This can occur when the battery has been used for a period of time, or if it has been stored for a long time without being used.

Can a battery's power transformation be reversed?

No, a battery's power transformation cannot be reversed. Once a battery has been drained, it must be recharged by applying an external electrical current, which will cause the chemical reactions to occur in the opposite direction, restoring the battery's power.

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