Solving the Resistance of an Electric Water Heater

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SUMMARY

The discussion focuses on calculating the resistance of an electric water heater's heating element, which heats 137 kg of water from 20°C to 45°C in 16 minutes, using a 220-V potential difference. The relevant equations include Q = mcΔT for heat transfer and R = V/I for resistance. Participants emphasize the importance of calculating power using the relationship between voltage, resistance, and time. The solution involves applying calorimetry principles alongside electrical relations to derive the resistance value.

PREREQUISITES
  • Understanding of calorimetry principles, specifically Q = mcΔT.
  • Familiarity with Ohm's Law, particularly R = V/I.
  • Knowledge of electrical power calculations, including P = V²/R.
  • Basic skills in unit conversions, especially time from minutes to seconds.
NEXT STEPS
  • Learn how to apply calorimetry in practical scenarios.
  • Study the relationship between power, voltage, and resistance in electrical circuits.
  • Explore advanced topics in thermodynamics related to heat transfer.
  • Investigate the efficiency of electric heating elements in various applications.
USEFUL FOR

Students in physics or engineering, electrical engineers, and anyone involved in designing or analyzing electric heating systems.

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Homework Statement


A well-insulated electric water heater warms 137 kg of water from 20°C to 45.0°C in 16.0 min. Find the resistance of its heating element, which is connected across 220-V potential difference.


Homework Equations


R=V/I


The Attempt at a Solution


Not sure how to approach this one. Should I refer to a calorimetry approach along with electrical relations? How might I start this one?

Any help/hints would be greatly appreciated.
 
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There is also an equation that relates the power to the voltage V and the resistance R.
On the other hand, you should be able to calculate the power from the given data.
 


Gotcha. Thanks for the hint. Looks like Q = mc delta T works great for calculating necessary heat to heat the water while v squared over R multiplied by time (in seconds) equals the heat generated by potential and resistance over time.

I appreciate your time in providing the hint.
 

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