Master Heat Transfer Laws: Fourier's, Newton's, and Stefan-Boltzmann's Laws

Question 1

According to Fourier's law of conduction, the heat transfer rate through a material is directly proportional to the:

Accepted Answer

Temperature gradient across the material

Answer

Cross-sectional area of the material

Answer

Thickness of the material

Answer

Density of the material

Question 2

The Stefan-Boltzmann law of radiation states that the total emissive power of a blackbody surface is directly proportional to the:

Accepted Answer

Surface temperature raised to the fourth power

Answer

Surface area of the object

Answer

Emissivity of the surface

Answer

Wavelength of the emitted radiation

Question 3

A heat exchanger is a device that:

Accepted Answer

Transfers heat between two fluids

Answer

Increases the temperature of a fluid

Answer

Decreases the temperature of a fluid

Answer

Generates heat

Question 4

The thermal conductivity of a material is a measure of its ability to:

Accepted Answer

Conduct heat

Answer

Store heat

Answer

Generate heat

Answer

Radiate heat

Question 5

The specific heat of a material is a measure of its ability to:

Accepted Answer

Store heat

Answer

Conduct heat

Answer

Generate heat

Answer

Radiate heat

Question 6

Which of the following materials has the highest thermal conductivity?

Accepted Answer

Copper

Answer

Aluminum

Answer

Steel

Answer

Wood

Question 7

Which law describes the relationship between heat transfer rate by conduction, temperature gradient, thermal conductivity, and cross-sectional area?

Accepted Answer

Fourier's Law of Conduction

Answer

Newton's Law of Cooling

Answer

Stefan-Boltzmann Law of Radiation

Answer

Kirchhoff's Law of Thermal Radiation

Question 8

Which of the following is NOT a recognized mode of heat transfer?

Accepted Answer

Sublimation

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 9

According to Newton's law of cooling, the rate of heat transfer from a hot object to its colder surroundings is proportional to:

Accepted Answer

Temperature difference between the object and the surroundings

Answer

Surface area of the object

Answer

Volume of the object

Answer

Density of the surroundings

Question 10

Which of the following surfaces has the highest emissivity?

Accepted Answer

Matte black paint

Answer

Polished aluminum

Answer

Human skin

Answer

Glass

Question 11

Which of the following units is commonly used to express thermal conductivity?

Accepted Answer

W/m-K

Answer

J/kg-K

Answer

m2/s-K

Answer

cal/g-K

Question 12

A heat sink is designed to:

Accepted Answer

Enhance heat dissipation from a surface

Answer

Reduce heat dissipation from a surface

Answer

Store heat for later use

Answer

Generate heat

Question 13

Which fundamental law describes heat transfer by conduction?

Accepted Answer

Fourier's law

Answer

Newton's law of cooling

Answer

Stefan-Boltzmann law

Question 14

Which of the following materials has the highest thermal conductivity?

Accepted Answer

Copper

Answer

Air

Answer

Glass

Answer

Wood

Question 15

The Stefan-Boltzmann law is associated with heat transfer by which mode?

Accepted Answer

Radiation

Answer

Convection

Answer

Conduction

Question 16

Which material is commonly used as an insulation due to its low thermal conductivity?

Accepted Answer

Polystyrene

Answer

Steel

Answer

Concrete

Answer

Water

Question 17

Why is thermal conductivity, the proportionality constant in Fourier's law of conduction, a crucial material property?

Accepted Answer

It determines the heat flow rate for a given temperature difference.

Answer

It represents the heat transfer rate per unit area.

Answer

It indicates the direction of heat flow.

Answer

It is the same for all materials.

Question 18

Newton's law of cooling describes the rate of heat transfer between a surface and its surroundings. This rate is proportional to the:

Accepted Answer

Temperature difference between the surface and the surroundings

Answer

Thermal conductivity of the fluid

Answer

Fluid velocity

Answer

Surface area of the object

Question 19

Which of the following processes involves the transfer of heat without the involvement of a physical medium?

Accepted Answer

Radiation

Answer

Mass transfer

Answer

Conduction

Answer

Convection

Question 20

The Stefan-Boltzmann law relates the emissive power of a blackbody to the:

Accepted Answer

Fourth power of its absolute temperature

Answer

Inverse square of its distance from the observer

Answer

Cube of its mass

Answer

Square of its surface area

Question 21

High thermal conductivity implies that a material:

Accepted Answer

Can transfer heat more efficiently

Answer

Stores heat more effectively

Answer

Is more resistant to temperature changes

Answer

Has a lower specific heat capacity

Question 22

Radiation heat transfer occurs through the emission and absorption of:

Accepted Answer

Electromagnetic waves

Answer

Fluid flow

Answer

Mechanical vibrations

Answer

Acoustic waves

Question 23

Which of the following dimensionless numbers characterizes the flow regime of a fluid?

Accepted Answer

Reynolds number

Answer

Thermal conductivity

Answer

Heat capacity

Answer

Stefan-Boltzmann constant

Question 24

In a composite wall consisting of multiple layers, the overall heat transfer rate is:

Accepted Answer

Inversely proportional to the sum of the thermal resistances of each layer

Answer

Directly proportional to the thickness of each layer

Answer

Dependent only on the material with the highest thermal conductivity

Question 25

The primary function of fins in heat transfer applications is to:

Accepted Answer

Increase the surface area for heat transfer

Answer

Generate heat internally

Answer

Reduce the thermal conductivity of the material

Answer

Prevent convection heat transfer