TINKER PiEDESIGN IN INDIA

Measure with a voltmeter and ammeterTinkerPieCircuit tutorial 6 of 24 · Intermediate · 15 minutes

Measure volts and current in a circuit and check Ohm's law: V = I × R.

Open this circuit in TinkerPieCircuit (free, runs in your browser)

What you will learn

Parts

1 battery (4.5 V)1 ammeter1 voltmeter1 resistor, 220 Ω1 LED

Steps

  1. Open the example

    Press the button below. The ammeter is in line with the battery. The voltmeter is across the resistor.

  2. Read the meters

    The ammeter shows about 11 mA. The voltmeter shows about 2.5 V.

  3. Check Ohm's law

    Divide: 2.48 V ÷ 0.0113 A = 220 Ω. That is the resistor value.

  4. Change the resistor

    Select the resistor and choose 470 Ω. The current drops. Calculate V ÷ I again.

This circuit needs no code. It runs by itself when you open it.

How it works

Ohm's law says voltage = current × resistance. The battery voltage splits between the resistor and the LED, so the resistor gets what the LED does not use.

Challenge: Move the voltmeter across the LED. What voltage do you see? (Hint: about 1.9 V for red.)

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