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Chapter 1: Q.1.28 (page 20)

Estimate how long it should take to bring a cup of water to boiling temperature in a typical 600-wattmicrowave oven, assuming that all the energy ends up in the water. (Assume any reasonable initial temperature for the water.) Explain why no heat is involved in this process.

Short Answer

Expert verified

Time is taken to boil2.616 minutes to raise the 20mlwater fromlocalid="1648467354265" 10掳Cto100掳C.

Step by step solution

01

Step 1. Finding Amount of heat.

Consider a mug filled with250mLcold10掳Cwater in a 600wattmicrowave. To achieve the boiling point, So must raise the temperature by90藲C.

Q=尘颁螖罢

m=Water mass.

C=Specific heat C=4.186J/g路C鈭�

螖罢=90掳Temp

Therefore,

Q=250脳4.186脳90=94185J.

02

Step 2. Boiling time.

The Power

P=Qt鈫�t=QP

Insert Qand Pvalues.

t=94185600=156.975s=2.616min.

Normally, heat is transferred from the hotter to the colder object. However, because there is no hot item in our scenario, the heat is transported to the mug via an electromagnetic wave generated by the magnetron.

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