Solve this multiple-choice question and choose the correct option.

Home » Mechanical Engineering » Heat Transfer, Refrigeration and Air Conditioning

Thermal radiation law: fill in Stefan–Boltzmann law wording Complete the statement: The total radiation from a black body per second per unit area is __________ the fourth power of its absolute temperature. Choose the correct phrase.

Difficulty: Easy

equal to
proportional to
inversely proportional to
independent of

Correct Answer: proportional to

Explanation:

Concept/ApproachStefan–Boltzmann law: E = σT⁴ for a black body, where σ is the Stefan–Boltzmann constant.

InterpretationThe phrasing is that emissive power is proportional to the fourth power of absolute temperature (with σ as the constant of proportionality).

Final Answerproportional to

← Previous Question Next Question→

More Questions from Heat Transfer, Refrigeration and Air Conditioning

Dalton’s law of partial pressures: write the correct relation Let p_b be barometric pressure, p_a the partial pressure of dry air, and p_v the partial pressure of water vapour in a gas mixture at the same location. Choose the correct equation.
Vapor-compression cycle component functions: where is heat rejected? During the standard refrigeration cycle, identify the component in which the refrigerant rejects heat to the surroundings. Choose the correct component.
Critical radius of insulation: effect on thermal resistance/heat flow For cylindrical/spherical insulation with external convection, at the critical insulation radius the thermal resistance to heat flow is at what condition? Choose the correct condition.
Free convection transition: identify the governing non-dimensional criterion For natural convection over surfaces, transition from laminar to turbulent flow is governed by a critical value of which parameter(s)? Choose the most appropriate option.
Humidity ratio (specific humidity): choose the correct basis Define humidity ratio/specific humidity as the mass of water vapour present in which reference amount? Choose the correct basis.
Concept check: dominant heat-transfer mode in solids Evaluate the statement: “In the case of solids, heat transfer takes place according to radiation.” Decide whether the statement is correct or incorrect and choose the best justification.
Definition identification: what correctly represents a heat pump? Select the description/device that best characterizes a heat pump in thermodynamics. Choose the correct option.
Refrigeration cycle state point: condition of refrigerant after the compressor and before the condenser Evaluate the statement about a vapor-compression system: “After leaving the compressor and before entering the condenser, the refrigerant is in the superheated-vapor state.” Choose whether this statement is correct.
Thermodynamic principle: which law dictates the direction of heat transfer? Identify the correct fundamental law governing heat flow from high temperature to low temperature. Choose the correct option.
Radiation fundamentals: parameters controlling emitted thermal radiation Which factors mainly affect the amount of thermal radiation emitted by a surface/body? Choose the correct option.

Discussion & Comments

No comments yet. Be the first to comment!

Join Discussion