1 Answer
In Class 12, when studying the effects of temperature on conductors, semiconductors, and insulators, here's how temperature influences each material:
1. Effect of Temperature on Conductors:
- Conductors (like metals) have free electrons that move and carry electric current.
- As temperature increases, the resistance of the conductor increases. This is because the atoms in the conductor vibrate more at higher temperatures, causing more collisions with the free electrons. This impedes the flow of electrons, increasing resistance.
- Example: Copper or aluminum conductors, which are commonly used in wires, have higher resistance at higher temperatures.
2. Effect of Temperature on Semiconductors:
- Semiconductors (like silicon and germanium) have a special property: their conductivity is between that of conductors and insulators.
- At low temperatures, semiconductors behave like insulators because very few charge carriers (electrons) are available for conduction.
- As temperature increases, the resistance of semiconductors decreases. This happens because more electrons get enough energy to jump from the valence band to the conduction band, making more charge carriers available for conduction.
- Example: At room temperature, silicon is a good semiconductor, but at very low temperatures, it acts more like an insulator.
3. Effect of Temperature on Insulators:
- Insulators (like rubber, wood, or plastic) have very few free electrons, so they don't conduct electricity well.
- At low temperatures, the resistance of insulators is very high because the atoms are closely packed and there are no free charge carriers to conduct electricity.
- At high temperatures, the resistance of insulators may decrease slightly because the increased thermal energy can cause some electrons to break free and contribute to conduction. However, insulators still remain poor conductors even at high temperatures, unless they reach a very high temperature (where they might start to behave like semiconductors).
In Summary:
This temperature dependence is a key difference between these materials.
1. Effect of Temperature on Conductors:
- Conductors (like metals) have free electrons that move and carry electric current. - As temperature increases, the resistance of the conductor increases. This is because the atoms in the conductor vibrate more at higher temperatures, causing more collisions with the free electrons. This impedes the flow of electrons, increasing resistance.
- Example: Copper or aluminum conductors, which are commonly used in wires, have higher resistance at higher temperatures.
2. Effect of Temperature on Semiconductors:
- Semiconductors (like silicon and germanium) have a special property: their conductivity is between that of conductors and insulators.- At low temperatures, semiconductors behave like insulators because very few charge carriers (electrons) are available for conduction.
- As temperature increases, the resistance of semiconductors decreases. This happens because more electrons get enough energy to jump from the valence band to the conduction band, making more charge carriers available for conduction.
- Example: At room temperature, silicon is a good semiconductor, but at very low temperatures, it acts more like an insulator.
3. Effect of Temperature on Insulators:
- Insulators (like rubber, wood, or plastic) have very few free electrons, so they don't conduct electricity well.- At low temperatures, the resistance of insulators is very high because the atoms are closely packed and there are no free charge carriers to conduct electricity.
- At high temperatures, the resistance of insulators may decrease slightly because the increased thermal energy can cause some electrons to break free and contribute to conduction. However, insulators still remain poor conductors even at high temperatures, unless they reach a very high temperature (where they might start to behave like semiconductors).
In Summary:
- Conductors: Resistance increases with temperature.
- Semiconductors: Resistance decreases with temperature.
- Insulators: Resistance remains very high, but may decrease slightly at higher temperatures.
This temperature dependence is a key difference between these materials.