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Ammeters and Voltmeters

Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 28 of 51.

An ammeter goes in series and has almost no resistance. A voltmeter goes in parallel, across what it measures, and has a very large resistance.

An ammeter and a voltmeter in a circuit

Ideal meters change nothing. A voltmeter whose resistance is near the resistor's is another resistor in parallel, and its reading drops.

Challenge

An ideal $9\ \mathrm{V}$ battery drives a current through a $3\ \mathrm{\Omega }$ and a $6\ \mathrm{\Omega }$ resistor in series. An ideal voltmeter is across the $6\ \mathrm{\Omega }$ resistor. What does it read? Call the reading $\relax V_{2}$ .

Try it yourself

Physics diagram: circuit

Solve for $V_{2}$

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Electricity and Magnetism

1Electric Charge and Force

Electric Charge Coulomb's Law Several Charges Recap - Charges in a Line

4Charged Conductors

The Charged Sphere Connecting Spheres Recap - Beam Between Plates

7Real Batteries

Internal Resistance The Variable ResistorAmmeters and VoltmetersRecap - Flashlight

10Magnetic Fields

Magnets and Magnetic Fields Field of a Wire Loops and Solenoids Recap - Electromagnet

2The Electric Field

The Electric Field Field of Several Charges The Uniform Field A Charge in a Uniform Field Recap - Stopping a Proton

5Capacitors

The Capacitor Combining Capacitors Changing a Capacitor Recap - Camera Flash

8Kirchhoff's Laws

The Junction Rule The Loop Rule Solving Two Loops Recap - Charging a Battery

11Magnetic Forces

Force on a Moving Charge Circles in a Field Force on a Wire Two Parallel Wires Recap - Current Balance

3Energy and Potential

Electric Potential Energy Electric Potential Field and Potential Recap - Accelerating Ions

6Current and Resistance

Current and Voltage Resistance and Ohm's Law Series and Parallel Electric Power Recap - Fairy Lights

9Capacitors in Circuits

A Capacitor in a Circuit Charging a Capacitor Discharging a Capacitor Recap - Defibrillator

12Induction

A Rod Moving in a Field Magnetic Flux Faraday's Law Lenz's Law Recap - Generator