Concepts of Physics

IIT JEE Physics (1978-2018: 41 Years) Topic-wise Complete Solutions

Conduction of Heat

Objective

To see how heat travels along a solid object

Introduction

When a solid object is heated at one point, the heat gets transferred from this point to the surrounding colder areas. This process continues until entire object become equally hot. This mode of heat transfer is called conduction.

Apparatus

hacksaw blade or steel scale, small nails, candle

Procedure

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Take a rod or flat strip of a metal, say of aluminium or iron. Fix a few small nails on the strip with the help of wax. These pieces shall be at nearly equal distances. Clamp the rod to a stand. If you do not find a stand, you can put one end of the rod in between bricks. Now, heat the other end of the rod and observe.

What happens to the nails? Do these begin to fall? Which nail fall first? Do you think that heat is transferred from the end nearest to the flame to the other end?

Discussion

The hacksaw blade is made up of metal. The atoms in metals are closely packed. When the blade is heated up by the flame, the atoms absorb heat energy, starts vibrating rapidly transferring part of the energy to the neighboring atoms. The heat energy is transferred from the hot region to the cold region.