Ohm's Law & Circuits

What you will investigate

This Ohm's law virtual lab connects circuit construction with current, voltage, resistance, and power measurements. Place meters correctly, record a current–voltage comparison, and investigate series, parallel, and mixed networks. The course distinguishes an ohmic resistor from a tungsten lamp, so a familiar circuit formula is applied with its conditions rather than assumed to describe every component at every setting.

An ammeter belongs in the relevant series path, while a voltmeter measures a potential difference across the component or section of interest. Their connections affect the circuit. A meter placed incorrectly is not merely a label in the wrong location; it can change the current or produce a fault. Explain the measuring setup before interpreting a number on its display.

A mixed circuit and an ideal power comparison

The opening comparison has lamp A in series with a parallel branch containing lamps B and C. In the ideal ohmic example, each lamp has resistance 10 Ω and the supply is 3.0 V. Use the complete network to predict current and power rather than giving every lamp the same supply voltage automatically.

Ideal opening circuit component	Current	Power
Lamp A	0.2000 A	0.4000 W
Lamp B	0.1000 A	0.1000 W
Lamp C	0.1000 A	0.1000 W

These are model validation values for the specified ohmic setup. They are not measurements from physical incandescent bulbs. The branching divides current, and the series component has a different voltage drop and power. The course links brightness reasoning with P = IV rather than using position in a drawing as an explanation.

Removing a branch can change different lamps differently

When lamp C is removed from this ideal network, lamps A and B carry 0.1500 A and each dissipates 0.2250 W. The change makes A dimmer and B brighter under the model's power interpretation. Removing one lamp therefore does not justify a general statement that every remaining lamp must get brighter or every remaining lamp must get dimmer.

Explain the result by finding the new equivalent resistance and the changed voltage distribution. The same component can receive a different fraction of the supply after the topology changes. Track the whole network before comparing the component's own power.

Graphs, conservation, and the battery model

For an ohmic component, a suitable current–voltage graph supports a constant-resistance interpretation. State which quantity is on each axis before converting slope to resistance. A tungsten-filament model can show a different relationship because its resistance changes with the operating conditions. A curved graph is a reason to revisit the constant-resistance assumption, not automatically evidence of a faulty instrument.

The node comparison reflects charge conservation and the loop comparison reflects energy conservation. The course's power account connects supply output with the contributions of the components. In the nonideal battery comparison, internal resistance helps explain why terminal voltage can be lower than the emf. A reading at the terminals and the battery's emf are related quantities but should not be substituted for each other without considering current.

Standards and classroom discussion

The main connections are New York HS-PS3-6 and AP Physics circuit topics. Ask students to defend a meter connection, interpret a graph, and explain the opening network using both currents and power. Then compare a changed topology with the original under matching assumptions. Ideal ohmic and Real-mode records have different roles; retain the component and supply conditions when drawing a conclusion. Continue with magnetic fields of currents or electrochemical cells.

Build an explanation from your records

Make a prediction before changing the conditions, then record a comparison that actually tests it. Keep the conditions attached to each row: a number without its setup can be misleading even when the arithmetic is correct. Explain what changed, what stayed fixed, and which observation supports your conclusion. If the result differs from your prediction, revise the explanation using the evidence rather than choosing a new answer without a reason.

The reference examples on this page describe the course model or its stated source data. They are not measurements collected from a physical laboratory by the reader. Compare like conditions, keep units visible, and distinguish rounded instrument displays from underlying model quantities. Use the investigation's stated limits when deciding whether a result can be generalized beyond the simulated setup. This guide supports preparation and interpretation; practical laboratory technique and safety training remain separate learning activities.