name the factors on which the increase in length of a rod, when heated, depend?
Answers
Imagine that a long, thin metal wire is heated. The wire expands. The amount by which it expands depends on three factors: its original length, the temperature change, and the thermal (heat) properties of the metal itself.
Some substances simply expand more easily than others. If you heat wires of aluminum, iron, and tungsten metals—all the wires being the same size and heated to the same temperature—each wire will expand by a different amount. The ease with which a substance expands is given by its coefficient of expansion. For comparison, the coefficients of expansion for aluminum, iron, and tungsten are 23 × 10 −6 , 12 × 10 −6 , and 5 × 10 −6 per degree Celsius, respectively.
The values given in the previous sentence actually refer to the coefficients of linear expansion. They measure how much a substance expands in only one direction. But suppose the above experiment were done with blocks of aluminum, iron, and tungsten rather than wires. In that case, the expansion would occur in all three directions: length, width, and depth. The measure of expansion in all three directions is called the coefficient of volume expansion.
Length and temperature. Suppose this discussion is limited to a single kind of material, say an iron wire. The amount by which that wire expands when heated depends on only two factors: its original length and the temperature to which it is heated. An iron bar that is 16 feet (5 meters) long will expand more than a bar that is 3 feet (1 meter) long. And a 16-foot (5-meter) bar will expand more if heated by 68°F (20°C) than a 16-foot (5-meter) bar that is heated by 50°F (10°C).