Current–Voltage (IV) Characteristics Flashcards

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What does an I–V characteristic show?

It shows how current changes when the voltage across a component changes.

On an I–V graph, which quantity goes on each axis?

Current, I, on the y-axis. Voltage, V, on the x-axis.

What does a straight line through the origin on an I–V graph mean for a resistor at constant temperature?

Current is proportional to voltage, so resistance is constant. It is an ohmic conductor.

What does a non-linear I–V characteristic mean?

The graph is not a straight line, so resistance changes as current or voltage changes.

How does a filament lamp’s I–V graph look, and why?

It curves and gets less steep at higher voltages because the filament heats up and its resistance increases.

How does a diode’s I–V characteristic behave?

It conducts in one direction only. In forward bias little current flows until a small threshold, then it rises fast. In reverse bias the current is almost zero.

In the I–V practical, where do you place the ammeter?

In series with the component to measure the current through it.

In the I–V practical, where do you place the voltmeter?

In parallel across the component to measure the voltage.

Why use a variable resistor in the I–V practical?

To change the voltage and current so you can record several I and V pairs.

How do you find the resistance at a point on an I–V graph?

Use R = V ÷ I at that point on the graph.

Why should you keep the temperature of a resistor constant during I–V measurements?

Heating changes resistance. Keeping temperature constant keeps the I–V graph reliable.

How can you get results for both positive and negative values on an I–V graph?

Reverse the power supply connections to swap the polarity and repeat the readings.