Microwave ovens operate by rapidly aligning and reversing water molecules within the food, resulting

1
Example (5.33)

• Microwave ovens operate by rapidly aligning and
  reversing water molecules within the food,
  resulting in volumetric energy generation.
• Consider a frozen 1-kg spherical piece of ground
  beef at an initial temperature of Ti-20C.
  Determine how long it will take the beef to reach
  a uniform temperature of T0C, with all the
  water in the form of ice. Assume that 3 of the
  oven power (P1kW total) is absorbed by the food.
• After all the ice is converted to liquid,
  determine how long it will take to heat the beef
  to Tf80C, if 95 of the oven power is absorbed.