(a) temperature is reduced
(b) temperature is increased
(c) free electrons become less
(d) free electrons become more
Correct Answer: (b) temperature
is increased
Explanation
Copper has a positive temperature
coefficient, so resistance increases with temperature.
Notes for
More Information
Concept: Effect of Temperature
on Resistance (Copper)
1. Copper is a
metallic conductor.
2. Metals like
copper have a positive temperature coefficient of resistance.
3. This means
that when temperature increases, resistance also increases.
Why Resistance of Copper
Increases with Temperature
4. When
temperature rises, copper atoms (positive metal ions) start
to vibrate more vigorously.
5. The
increased vibration causes more frequent collisions between:
·
Free electrons (current carriers)
·
Vibrating copper atoms
6. These
collisions oppose the motion of electrons.
7. As a
result, the flow of current becomes more difficult.
8. This
appears as an increase in electrical resistance.
Resistance (Definition)
9. Resistance is
the property of a conductor that opposes the flow of electric current.
10.
It is denoted by R.
11.
The SI unit of resistance is ohm (Ω).
Formula for Resistance
12.
The resistance of a conductor is given by:
13.
Where:
= resistivity of the conductor
= length of the conductor
= cross-sectional area
Effect of Temperature on
Different Materials
Conductor (Metals)
14.
When the temperature increases, the resistance
increases.
15.
Hence, metals have a positive temperature coefficient.
Insulator
16.
When the temperature increases, the resistance
decreases.
17.
This is because more charge carriers become available.
Semiconductor
18.
When the temperature increases, the resistance
decreases.
19.
This is due to the generation of more charge carriers (electrons and
holes).
Conclusion
20.
Copper, being a metallic conductor, shows an increase
in resistance with increase in temperature.
21.
This behavior is due to increased atomic vibrations and electron
collisions.
22.
Therefore, copper has a positive temperature coefficient of
resistance.