Resistivity

Question 1

why does electrical heating occur?

Answer 1

• 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

Question 2

what is the resistance equation?

Answer 2

R = pL / A

R - resistance
p - resistivity
L - length of wire
A - cross sectional area

Question 3

why does current decrease as temperature of a material increases?

Answer 3

• 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

Question 4

for an ohmic conductor which is a metal:

Answer 4

• an increase in temperature causes an increase in resistance
• a decrease in temperature causes a decrease in resistance

Question 5

how does a thermistor behave differently?

Answer 5

• an increase in temperature causes a decrease in resistance

Question 6

what is a superconductor?

Answer 6

• a material with no resistance below a critical temperature

Question 7

what is the critical temperature?

Answer 7

• temperature at which a material becomes superconductive