Resistance and V=IR Flashcards
Describe the relationship between the current through a resistor and the potential difference
The current through a resistor (at a constant temp) is directly proportional to P.D
Describe the graph for different resistors (V = x-axis, I = y-axis)
Straight, positive lines through the origin. Different slopes on different lines because different resistors have different resistances.
Describe the graph for a filament lamp (V = x-axis, I = y-axis)
Like a sin graph from sin(-90) to sin(90)
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Describe the relationship between a filament lamp (temperature) and resistance
As the temp. of the filament increases, the resistance increases
Describe current and resistance in a diode
Current will only flow in 1 direction through a diode. The diode has a very high resistance in the opposite direction
Describe the graph for a filament lamp (V = x-axis, I = y-axis)
Flat line of y=0 until the origin where it increases in a positive curve, steeper than exponentially
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Resistance increases with [ ]
Temperature
What happens when an electrical charge flows through a resistor? (Energy)
Some of the electrical energy is transferred to heat energy and the resistor gets hot. The heat causes the ions in the conductor to vibrate more.
Why does resistance increase as temp. increases?
The heat (of the resistor) causes the ions in the conductor to vibrate more. This makes it more difficult for the charge-carrying electrons to get through the resistor - the current can’t flow as easily and the resistance increases
For most resistors there’s a limit to the amount of [ ]
current that can flow
More current means an…
Increase in temperature, which means an increase i resistance, which means the current decreases again
What is the formula for potential difference?
P.D = Current * Resistance V = IR Current = Amps, A P.D = Volts, V Resistance = Ohms, Ω
What does a straight line graph tell you about the resistance?
It is steady
