I-V graphs

Question 1

What is the I-V graph for a resistor and why?

Answer 1

• Straight line through the origin
• V = I x R
• As the only component is a resistor, the resistance will be constant. Therefore, as voltage increases, current will also increase proportionally

Question 2

What is the I-V graph for a filament bulb and why?

Answer 2

• Line through the origin which curves plateaus
• As the voltage increases, the wire gets hotter which in turn increases the resistance, acting to decrease the current

Question 3

What is the I-V graph for a diode and why?

Answer 3

• Line ONLY in the positive quadrant and curves up
• Has a very high resistance in the opposite direction so only lets current flow in one direction