Module 4 - EPR (Resistance)

Question 1

What is meant by the term Resistance

Answer 1

The opposition to the flow of charge

Question 2

What is the unit for resistance

Answer 2

ohm (Ω)

Question 3

Describe and explain the relationship between current and Resistance

Answer 3

High resistance means a higher opposition to the flow of charge so less charge can flow, so the currentis lower:

R α 1/I

Question 4

Describe and explain the relationship between Potential difference and Resistance

Answer 4

High resistance means a higher opposition to the flow of charge, this means that more energy is needed per unit charge to overcome the resistance:

R α V

Question 5

What is Ohm’s Law

Answer 5

For a constant temperature the current is directly proportional to the potential difference in the circuit

Question 6

IV graph of a resistor

Answer 6

y = mx, because it is an ohmic conductor, so has a constant temperature and no increase or decrease in resistance so I α V

Question 7

IV graph for a filament lamp

Answer 7

As the potential diffference increases the current increases at a decreasing rate because as more current flows there are more collisions to the positive metal ions causing them to vibrate more and transfer more energy as heat causing the resistance to increase , making it harder for current to flow

Question 8

IV graph for a Diode

Answer 8

As the p.d increase the current remains 0 until the threshold voltage is met, then as the pd increases the current increases at a decreasing rate current flows there are more collisions to the positive metal ions causing them to vibrate more and transfer more energy as heat causing the resistance to increase , making it harder for current to flow

Question 9

IV graph for a thermistor

Answer 9

As the potential difference increases the current in the circuit increases this is because more current means more collisions with the positive metal ions causing them to vibrate more and dissapate more heat, as the temperature increases the resistance decreases due to the number density of the charge carriers in the material increasing as a result of more charge carriers being released.

Question 10

IV graph for LDR

Answer 10

As the potential difference increases the current in the circuit increases this is because more current means more light emits, this causes the resistance to decrease due to the number density of the charge carriers in the material increasing as a result of more charge carriers being released.

Question 11

What does the gradient of an IV graph represent

Answer 11

1/R