Examkin

Question

Difficulty: EasyThermodynamics and Heat

An electric toaster toasts bread using glowing heating coils placed a short distance away from the slices without touching them. Which method of heat transfer is primarily responsible for warming and toasting the bread?

  1. A
    Conduction
  2. B
    Convection
  3. RadiationAnswer
  4. D
    Condensation

Answer

Radiation transfers thermal energy across the space between the coils and the bread via electromagnetic infrared waves.
Thermal radiation transfers energy via electromagnetic waves, such as infrared light. Because the bread does not touch the glowing wires, radiation is the primary mechanism heating the surface of the bread directly across the gap.

Step-by-Step Solution

1
Analyze the physical arrangement in the toaster.
The bread is placed near the glowing elements across an air gap without making direct physical contact.
Determining whether physical contact occurs narrows down the possible heat transfer mechanisms.
2
Identify the primary mechanism of heat transfer through empty space and transparent air.
The glowing heating elements emit electromagnetic energy in the form of infrared radiation directly onto the bread's surface.
Thermal radiation does not require direct contact or fluid circulation currents to transfer energy.

Key Concept

Thermal radiation transfers heat through electromagnetic waves without requiring direct contact or a circulating medium.
Estimated Time:45s
Rate this question

Topics

Thermodynamics and Heat

More questions from this topic