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An electric iron of resistance 50 ohm generates 378 kilocalorie of heat in 30 minutes. What is the voltage of the mains?

User Tawanna
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1 Answer

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The voltage of the mains supplied to the iron is determined as 209.6 V.

How to calculate the voltage of the mains?

The voltage of the mains is calculated by applying the following formula as shown below;

P = V²/R

where;

  • V is the voltage of the mains
  • R is the resistance of the iron
  • P is the power supplied

The power supplied by the mains is calculated as follows;

P = E / t

P = ( 378 kcal x 4184 J/kcal) / (30 min x 60 s / min)

P = (1,581,552 ) / (1800 s)

P = 878.64 W

P = V²/R

V² = PR

V = √PR

V = √ (878.64 x 50)

V = 209.6 V

User Chris Conlan
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