Physics · Practical apparatus

Forward and reverse diode meters

Reverse the virtual polarity and compare the voltage and current ranges. The resistor limits forward current. A reverse microamp reading is much smaller than the forward milliamps and needs a different meter scale.

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Forward and reverse diode meters

டையோடின் துருவத்தை மாற்றி முன்னோக்கு மில்லியம்பியர் மற்றும் பின்னோக்கு மைக்ரோம்பியர் வாசிப்புகளை ஒப்பிடவும்.

Key notes, relationships and model limits

Key relationship

Forward I≈max(0,Vs−0.7)/R; reverse I≈−2 μA before breakdown.

Practical tip

Common trap

This model does not include the reverse breakdown regime.

Model limits

Virtual silicon constant-drop diode and fixed reverse leakage; no reverse breakdown. Source includes the displayed current-limiting resistor. Graph sweeps the signed bias source voltage with this same resistor-limited teaching approximation.

What you will learn

Compare forward and reverse meter readings during a source-voltage sweep.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

2 V source,0.7 V drop and1 kΩ gives1.3 mA forward current.

Why this matters

The model connects forward and reverse diode meters with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

The series resistor is used to?

Increase current without limit
Limit diode current
Remove polarity dependence

Read the explanation

The source excess voltage drops across the resistor.

Course connection: Virtual apparatus preparation. Check exact board/exam membership in the syllabus sources. Physical practical work remains necessary.