It simply means:
How the electric current (I) flowing through a component changes when you apply different voltages (V) across it.
You slowly increase the voltage, and watch what the current does.Then you draw a graph of current (I) on one side, and voltage (V) on the other.
This graph tells you a lot about the behavior of that component.
🧠 Think of it Like This:
Voltage is like a push.
Current is like how fast the electrons are flowing.
If you push harder, does more current flow?Yes — but it depends on the thing you're pushing the current through.That’s what the I–V graph shows.
🧪 Let’s See Different Kinds of I–V Characteristics:
1. Ohmic Resistor (like a normal wire or resistor)
This follows Ohm’s Law:
I=VRI = \frac{V}{R}I=RV
The graph is a straight line.
If you double the voltage, the current also doubles.
This is called linear behavior.
👉 Such materials are called Ohmic conductors.
2. Non-Ohmic Components (like diodes, filament bulbs, etc.)
These do not follow Ohm’s Law perfectly.
Filament bulb: As voltage increases, the wire heats up, so resistance increases.The graph curves — current doesn't increase evenly.
Diode: It lets current flow only in one direction.The graph looks like a sharp curve in one direction, and flat in the other.
👉 These are called non-ohmic devices because resistance changes with voltage.
📈 What Does the I–V Graph Tell Us?
Slope of the graph = related to resistance(steeper slope = less resistance, flat slope = high resistance)
Straight line = constant resistance
Curved line = changing resistance
You can look at the graph and immediately know:
Is this component obeying Ohm’s Law?
Does it behave differently at high or low voltages?
Is it working like a switch (diode), heater (bulb), or something else?
💡 Why It Matters in Real Circuits:
Engineers design circuits using these graphs.
To control current, avoid overheating, or create logic for computers.
To know how a device responds when voltage is applied.
🔍 Summary:
Current–Voltage characteristics show how current changes with applied voltage.
For ohmic devices (resistors), the graph is a straight line.
For non-ohmic devices (bulbs, diodes), the graph is curved or weird-shaped.
It helps us understand and control how electronic parts behave.
A resistor has a straight-line I–V graph because it obeys Ohm’s Law with constant resistance.
A filament bulb’s graph curves since its resistance increases as it heats up.
A diode’s graph is flat until a threshold, then rises sharply, as it only allows current in one direction.
Ohm’s Law holds only when resistance stays constant, so some devices follow it at certain voltages but not always.
How does the I–V characteristic of a resistor differ from that of a diode or a filament bulb, and what does this tell us about their behavior?
Why is the I–V graph of an ohmic conductor a straight line, and what does its slope represent?
Can a component obey Ohm’s law at some voltages but not at others? Explain with examples.