Question

Heat travels through vacuum by:

• A. Conduction
• B. Convection
• C. Radiation
• D. Both (A) and (B)

Answer 1

Answer:

C. Radiation

Radiation

• Heat transfer through radiation does not require any medium.

• It can travel through a vacuum, such as outer space.

• This is the primary way the Sun's heat reaches Earth.

• Radiation involves the emission of electromagnetic waves (like infrared radiation) which carry energy.

• All objects above absolute zero temperature emit thermal radiation.

• The rate of radiation depends on the object's temperature, surface area, and surface properties (emissivity).

Conduction

• Heat transfer through direct contact of particles.

• Requires a material medium (solid, liquid, or gas).

• Occurs mainly in solids where particles are closely packed.

• Examples: Heating a metal rod at one end; heat transferring to the other end.

Convection

• Heat transfer through the movement of fluids (liquids or gases).

• Requires a material medium.

• Warm, less dense fluid rises, and cooler, denser fluid sinks, creating convection currents.

• Examples: Boiling water; air circulation in a room due to a heater.