What is the power - the rate at which it supplies electrical energy?

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Homework Help Overview

The problem involves calculating the power output of a solar cell given its emf, current, and the duration of operation. The subject area pertains to electrical energy and power calculations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of power using the formula P = IV and question the correctness of the energy value provided. There is an emphasis on ensuring unit conversions are applied correctly.

Discussion Status

Some participants have confirmed similar calculations for power, while others are verifying the energy value. There is an ongoing exploration of the relationships between power, energy, and time.

Contextual Notes

Participants note the importance of converting units from milliamperes to amperes and hours to seconds, which may affect the calculations.

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Homework Statement


A solar cell provides an emf of 0.70 V.
If the cell supplies a constant current of 20.5 mA for 8.0 h, how much electrical energy does it supply? 413.3 J
What is the power - the rate at which it supplies electrical energy?

Homework Equations



P=work/time
units J/s
i keep getting .014

The Attempt at a Solution

 
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Indeed. Is the 413.3 correct? I'll run a calculation n see what I come up with.
 


Use P = IV to find the power (current in Amperes x potential in Volts).
Electric potential is sometimes called "electromotive force" or "voltage".

Energy is Pt (power x time).
These concepts are often confused with each other. Power is the rate at which energy is provided (or work is done). It is measured in units of Joules per second (also called watts).

Don't forget to convert your mA into A, hours into seconds before using them!
 


That's what I get too, 0.0144 W. The energy (413.3 J) per time (8hrs = 8*60*60 secs).
 


Thanks!
 

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