Fourier Equation And Thermal Conductivity Online Exam Quiz

Important questions about Fourier Equation And Thermal Conductivity. Fourier Equation And Thermal Conductivity MCQ questions with answers. Fourier Equation And Thermal Conductivity exam questions and answers for students and interviews.

The diagram shows heat conduction through a plane wall. The surface temperature is 475 K and it radiates heat to the surroundings at 335 K. If thermal conductivity of the material is 12.5 W/m degree, find the temperature gradient. Let convective coefficient be 80 W/m² degree and radiation factor is 0.9

Options

A : a. – 1052.4 degree celsius

B : b. – 2052.4 degree celsius

C : c. – 3052.4 degree celsius

D : d. – 4052.4 degree celsius

From the concept of kinetic theory, mean travel velocity of the gas molecules is prescribed by the relation (Where, G = Universal gas constant M = Molecular weight of the gas T = Absolute temperature)

Options

A : a. V = (3M/GT)??

B : b. V = (3GT/M)??

C : c. V = (6T/GM)??

D : d. V = (3GT/2M)??

Low temperature insulation are used when the enclosure is at a temperature lower than the ambient temperature. Which one of the following is not a low temperature insulation?

Options

A : a. Asbestos

B : b. Cork

C : c. Cattle hair

D : d. Slag wool

The value of Lorenz number in 10¯? W ohms/K² is

Options

A : a. 2.02

B : b. 2.35

C : c. 2.56

D : d. 2.45

Consider the following parameters (i) Composition (ii) Density (iii) Porosity (iv) Structure Then, thermal conductivity of glass wool varies from sample to sample because of variation is

Options

A : a. 1 and 2

B : b. 1, 2, 3 and 4

C : c. 1 and 3

D : d. 1, 2 and 3

The thermal conductivity and the electrical conductivity of a metal at absolute temperature are related as

Options

A : a. k/? T

B : b. k/?

C : c. k ?/T

D : d. k/T

The relation ?² t =0 is referred to as

Options

A : a. Poisson’s equation

B : b. Fourier heat conduction equation

C : c. Solution for transient conduction

D : d. Laplace equation

To effect a bond between two metal plates, 2.5 cm and 15 cm thick, heat is uniformly applied through the thinner plate by a radiant heat source. The bonding must be held at 320 K for a short time. When the heat source is adjusted to have a steady value of 43.5 k W/m², a thermocouple installed on the side of the thinner plate next to source indicates a temperature of 345 K. Calculate the temperature gradient for heat conduction through thinner plate. In the diagram, the upper plate is 2.5 cm thick while the lower is 15 cm thick.

Options

A : a. – 1000 degree Celsius/m

B : b. – 2000 degree Celsius/m

C : c. – 3000 degree Celsius/m

D : d. – 4000 degree Celsius/m

The diffusion equations ?²t + q g = (1/?) (d t/d r) Governs the temperature distribution under unsteady heat flow through a homogenous and isotropic material. The Fourier equation follows from this expression when

Options

A : a. Temperature doesn’t depends on time

B : b. There is no internal heat generation

C : c. Steady state conditions prevail

D : d. There is no internal heat generation but unsteady state condition prevails

The famous Fourier series is named after

Options

A : a. Diller and Ryan

B : b. J.B. Joseph Fourier

C : c. Stefan- Boltzmann

D : d. Wein’s

Fourier law of heat conduction is best represented by

Options

A : a. Q = -k A d t /d x

B : b. Q = k A d x/d t

C : c. Q = -k A

D : d. Q = k d t/d x

Here are some assumptions that are made for Fourier law. Identify the wrong one

Options

A : a. No internal heat generation

B : b. Steady state heat conduction

C : c. Non- linear temperature profile

D : d. Isotropic and homogenous material

Consider the following statements: The Fourier heat conduction equation Q = -k A d t /d x Presumes i) Steady state conditions ii) Constant value of thermal conductivity iii) Uniform temperature at the wall surface iv) One dimensional heat flow Which of these statements are correct?

Options

A : a. 1, 2 and 3

B : b. 1, 2 and 4

C : c. 2, 3 and 4

D : d. 1, 3 and 4

Negative sign in Fourier heat conduction equation indicates

Options

A : a. Heat always flow is in the direction of positive temperature gradient

B : b. Heat always flow in the direction of negative temperature gradient

C : c. No heat flow is there

D : d. Data is insufficient

Transmission of heat i.e. molecular is smallest in case of

Options

A : a. Gases

B : b. Liquids

C : c. Alloys

D : d. Solids

Which one is not the unit of thermal conductivity?

Options

A : a. kcal/m hr K

B : b. KJ/m hr K

C : c. W/m s K

D : d. Cal/cm s K

“Thermal conductivity represents the amount of heat conducted across unit area when a temperature difference of one kelvin”. True or false

Options

A : a. True

B : b. False

C : c. May be

D : d. Can't say

Which of the following is the unit of thermal resistance?

Options

A : a. degree/kcal

B : b. hour degree

C : c. s degree/kcal

D : d. degree/W

Thermal conductivity is defined as the heat flow per unit time

Options

A : a. When temperature gradient is unity

B : b. Across the wall with no temperature

C : c. Through a unit thickness of the wall

D : d. Across unit area where temperature gradient is unity

Mark the matter with least value of thermal conductivity