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The resistance wire of a 1200 W hair dryer is 80 cm long and has a diameter of 0⋅3 cm. What is the rate of heat generation in the wire per unit volume?

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  1. 212 W/cm3
  2. 312 W/cm3
  3. 512 W/cm3
  4. 412 W/cm3

Answer (Detailed Solution Below)

Option 1 : 212 W/cm3
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Detailed Solution

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Concept:-

The rate of heat generation in the wire per unit volume is given by,

Calculation:

Given:

Rating = 1200 W

Length = 80 cm

Diameter = 0.3 cm

Now on putting all the values in the formula,

→ 

The volume of the cylindrical resistance wire is,

V = πD2L/4

Volume =  

Volume = 5.655 cm3

Heat generation in the wire per unit wire is,

⇒  W/cm3

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