Which heat transfer mode transfers heat through solids?

• A. Conduction
• B. Convection
• C. Radiation
• D. Evaporation

Answer: (A)

Conduction is the mode that transfers heat through solids. In a solid, particles are tightly packed, so energy moves from a hotter region to a cooler region through direct interactions—vibrations of the lattice and, in metals, free electrons shuttling energy along the material. This internal transfer happens without any bulk fluid motion or electromagnetic waves traveling through space.

Convection needs a fluid in motion, so it doesn’t describe heat moving inside a solid. Radiation transfers heat via electromagnetic waves and can occur through empty space, not confined to solids. Evaporation is a phase-change process from liquid to gas and isn’t a primary way heat moves through a solid.

So conduction best explains why heat travels through solid objects, like a heated metal rod warming along its length.