Resistance Flashcards
How do you recognise the resistor V-I graph?
The current through a resistor (at constant temperature) is directly proportional to potential difference
Straight line
How do you recognise the filament lamp V-I graph?
As the temperature of the filament lamp increases the resistance increases forming a curve
How do you recognise the diode V-I graph?
Current will only flow through diode in one direction so the diode had very high resistance in the opposite direction
Why does a resistor get hot?
When an electrical charge flows through a resistor some of the electrical energy is transferred to heat energy
What does this heat energy cause the ions to do?
Causes the ions in the conductor to vibrate more so it’s more difficult for the charge-carrying electrons to get through the resistor
Why does this increase resistance?
The current can’t flow as easily and resistance increases
What is the result of most resistors having a limit to the amount of current that can flow?
More current means an increase in temperature which increases resistance which consequently decreases the current
How do you work out potential difference?
Potential difference = current x resistance
V= I x R
What does the steeper the graph mean?
Lower the resistance as resistance of component is equal to the inverse of the gradient
What does it mean if the graph curves?
The resistance is changing and can be found for any point by taking the pair of values and using the formula
