lesson
Updated 6 days ago Β· 2 views
If you plug a power tool into a 100-foot extension cord, it often runs noticeably weaker than when plugged directly into the wall. Why does simply making a wire longer choke the flow of electric charge?
In 1827, German physicist Georg Ohm investigated how wire dimensions change current, discovering the direct relationship between potential difference, current, and resistance.
How do we build an experimental circuit to test this relationship for ourselves?
The Experimental Setup
To measure resistance, we place an ammeter in series to record the current through the test wire and a voltmeter in parallel across only the measured length.
We tape a thin resistance wire (like nichrome) to a meter stick and connect crocodile clips at each end of the length we want to test.
πCreate an interactive schematic of the wire resistance experiment. Display a meter stick labeled 0 to 100 cm with a straight wire taped along it. Show a DC power pack, a switch, an ammeter connected in series, and a voltmeter wired in parallel across two crocodile clips on the wire. Allow the user to drag the right crocodile clip along the meter stick to change the length (e.g., 20 cm, 40 cm, 60 cm, 80 cm). Display dynamic digital readouts for Voltmeter (V), Ammeter (A), and Wire Length (cm). Style with #1e2945 text, #e6e6e6 borders, clean white cards, soft blue highlights.
Once our circuit is connected, how do we turn those voltage and current readings into resistance values?
Measuring Resistance Along the Wire
Resistance measures how much a component opposes the flow of electric charge, calculated using Ohm's law formula: R=IVβ where R is resistance in ohms (Ξ©), V is potential difference in volts (V), and I is current in amperes (A).
We adjust the movable crocodile clip in regular intervalsβtypically every 10Β cm from 10Β cm up to 100Β cmβrecording both meters at each step.
πDesign a step-by-step visual guide showing a table and wire diagram side-by-side. On the left, show the wire on a ruler with clip positions at 20 cm, 40 cm, and 60 cm. On the right, show a measurement card with columns: Length L (cm), Potential Difference V (V), Current I (A), and Calculated Resistance R = V/I (Ξ©). Include a clickable 'Next Length' button that animates the clip moving to the next interval and adds the calculated data row: 20 cm -> 0.40 V, 0.20 A -> 2.0 Ξ©; 40 cm -> 0.80 V, 0.20 A -> 4.0 Ξ©; 60 cm -> 1.20 V, 0.20 A -> 6.0 Ξ©.
What hidden factor can quietly ruin our measurements if we leave the circuit turned on?