Resistivity Flashcards
1
Q
why does electrical heating occur?
A
- as free electrons move through a metal wire. they collide with ions in their way
- as a result, they transfer some, or all of their kinetic energy on collision, causing electrical heating
2
Q
what is the resistance equation?
A
R = pL / A
R - resistance
p - resistivity
L - length of wire
A - cross sectional area
3
Q
why does current decrease as temperature of a material increases?
A
- all solids are made up of vibrating atoms, high the temperature, the faster the atoms vibrate
- electrons collide with the vibrating atoms, causing current to decrease
4
Q
for an ohmic conductor which is a metal:
A
- an increase in temperature causes an increase in resistance
- a decrease in temperature causes a decrease in resistance
5
Q
how does a thermistor behave differently?
A
- an increase in temperature causes a decrease in resistance
6
Q
what is a superconductor?
A
- a material with no resistance below a critical temperature
7
Q
what is the critical temperature?
A
- temperature at which a material becomes superconductive
8
Q
A
