Physics · Practical apparatus

Ammeter and voltmeter conversion

Choose the required range and derive the resistor to protect the sensitive coil. Check applied quantity against the chosen range before taking a reading; over-range values are visibly flagged.

Open the interactive experiment →

Ammeter and voltmeter conversion

உணர்திறன் கொண்ட கம்பிச்சுருளைக் காக்க சரியான இணை அல்லது தொடர் மின்தடை தேவை. அளவீடு தேர்ந்தெடுத்த வரம்பிற்குள் இருக்க வேண்டும்.

Key notes, relationships and model limits

Key relationship

S=IgG/(Irange−Ig); Rseries=Vrange/Ig−G.

Practical tip

Choose the required range and derive the resistor to protect the sensitive coil. Check applied quantity against the chosen range before taking a reading; over-range values are visibly flagged.

Common trap

Connect a shunt in parallel for an ammeter and a multiplier in series for a voltmeter. Check the converted meter’s range before taking a reading.

Model limits

ideal linear converted meters, no loading correction. Deflection is not clipped, so overload is explicit. The graph switches between applied-current and applied-voltage sweeps with meter type.

What you will learn

Adjust ammeter and voltmeter conversion apparatus, observe its reading and derive the indicated physical quantity.

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

For Ig=1 mA and G=100 Ω, a 10 V meter needs 9900 Ω in series and a 1 A meter needs ≈0.1001 Ω shunt.

Why this matters

The model connects ammeter and voltmeter conversion with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

A voltmeter conversion places the additional resistor?

In parallel with the coil.
In series with the galvanometer.
Across the source while bypassing the coil.

Read the explanation

In series with the galvanometer.

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