Properties of Solids & Liquids-Heat Transfer (NEET (NTA)-National Eligibility cum Entrance Test (Medical) Physics): Questions 36 - 39 of 40

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Question number: 36

» Properties of Solids & Liquids » Heat Transfer » Conduction

MCQ▾

Question

A 10 cm thick ice block is there on the surface of water in a lake. The temperature of air is - 10° C; how much time it will take to double the thickness of the block (L = 80 cal/g, K ice = 0.004 erg/s-k, ρ ice = 0.92 gm cm -3)

Choices

Choice (4) Response

a.

51.11 hours

b.

21 hour

c.

19.11 hours

d.

191 hours

Question number: 37

» Properties of Solids & Liquids » Heat Transfer » Conduction

MCQ▾

Question

Three rods of the same dimension have thermal conductivities 3K, 2K and K. They are arranged as shown in fig. with their ends at 100°C, 50°C and 20°C. The temperature of their junction is

Three rod of same dimension

Three Rod of Same Dimension

In above figure it is shown that three rod of same dimension have thermal conductivities 3K, 2K and K.

Choices

Choice (4) Response

a.

70°C

b.

60°C

c.

50°C

d.

35°C

Question number: 38

» Properties of Solids & Liquids » Heat Transfer » Convection

MCQ▾

Question

A cylindrical rod with one end in a steam chamber and its other end in ice results in melting of 0.1 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 ¼ that of firth, the rate at which ice melts in gm/sec will be

Choices

Choice (4) Response

a.

0.1

b.

1.6

c.

0.2

d.

3.2

Question number: 39

» Properties of Solids & Liquids » Heat Transfer » Conduction

Assertion-Reason▾

Assertion (Ꭺ)

The equivalent thermal conductivity of two plates of same thickness in contact (series) is less than the smaller value of thermal conductivity.

Reason (Ꭱ)

For two plates of equal thickness in contact (series) the equivalent thermal conductivity is given by

Choices

Choice (4) Response

a.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

b.

Ꭺ is true but Ꭱ is false

c.

Both Ꭺ and Ꭱ are false

d.

Ꭺ is false but Ꭱ is true

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