Properties of Solids & LiquidsHeat Transfer (NEET (NTA)National Eligibility cum Entrance Test (Medical) Physics): Questions 5  8 of 40
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Question number: 5
» Properties of Solids & Liquids » Heat Transfer » Radiation
Question
An ice box used for keeping eatable cold has a total wall, area of 1 meter ^{2} and a wall thickness of 5.0 cm. The thermal conductivity of the ice box is K = 0.01 joule/meter °C is filled with ice at 0° C along with eatables on a day when the temperature is 30°C. The latent heat of fusion of ice is 334 × 10 ^{3} joules/kg. The amount of ice melted in one day is (1 day = 86, 400 seconds)
Choices
Choice (4)  Response  

a.  1552 gm 

b.  776 gm 

c.  11520 gm 

d.  7760 gm 

Question number: 6
» Properties of Solids & Liquids » Heat Transfer » Radiation
Question
f between wavelength λ and λ + dλ, e _{λ} and a _{λ} be the emissive and absorptive powers of a body and E _{λ} be the emissive power of a perfectly black body, then according to Kirchhoff’s law, which is true
Choices
Choice (4)  Response  

a. 


b. 


c. 


d. 


Question number: 7
» Properties of Solids & Liquids » Heat Transfer » Conduction
Question
A cylindrical rod with one end in a steam chamber and it other end in ice results in melting of 0.3 gm of ice per second. If the rod is replaced by another with half the length and double the radius of the first and if the thermal conductivity of material of second rod is that of first, the rate at which ice melts in gm/sec will be
Choices
Choice (4)  Response  

a.  3.2 

b.  0.6 

c.  0.1 

d.  0.2 

Question number: 8
» Properties of Solids & Liquids » Heat Transfer » Conduction
Question
A solid copper sphere (density ρ and specific heat capacity c) of radius r at an initial temperature 200 K is suspends inside a chamber whose walls are at almost 0 K. The time required (in µ s) for the temperature of the sphere to drop to 100 K is
Choices
Choice (4)  Response  

a. 


b. 


c. 


d. 

