Power, Voltage and Current - Hairdryer Problem

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SUMMARY

The discussion centers on calculating the number of 1500-W hair dryers that can operate on a household circuit rated for 30.0 A at 120 V. Using the formula P = VI, the total power capacity of the circuit is determined to be 3600 W. Dividing this by the power consumption of a single hair dryer (1500 W) yields 2.4, but the correct answer is 2 hair dryers, as only whole units are permissible. The confusion arises from the interpretation of the requirement for integer units.

PREREQUISITES
  • Understanding of electrical power calculations (P = VI)
  • Knowledge of household circuit specifications (30.0 A, 120 V)
  • Familiarity with power ratings of appliances (1500 W hair dryers)
  • Basic arithmetic skills for unit conversion and division
NEXT STEPS
  • Review electrical power formulas and their applications in household circuits
  • Explore the implications of circuit breaker ratings on appliance usage
  • Learn about the significance of integer units in practical applications
  • Investigate safety measures for using multiple high-wattage appliances on a single circuit
USEFUL FOR

Students studying electrical engineering, electricians, and homeowners looking to understand the limitations of household electrical circuits when using multiple high-wattage appliances.

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Homework Statement


A typical household circuit is capable of carrying 30.0 A of current at 120 V before the circuit breaker will trip. How many 1500-W hair dryers can run off one such circuit?

Use the relation between power, current and voltage. Also, remember hair dryers come in integer units.

Homework Equations


P = VI


The Attempt at a Solution


P = 120 * 30 = 3600
3600/1500 = 2.4

This is incorrect and I don't understand why. Am I missing something?
 
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What's 0.4 of a hairdryer?
 
Ah, thank you. I only put 2.4 because they said "Also, remember hair dryers come in integer units" so I thought they wanted the .4.

Thank you!
 

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