Internal Resistance and Terminal Voltage

Keep one non-ideal source and one load on screen so emf, internal drop, terminal voltage, current, and wasted power stay tied to the same one-loop circuit.

Explore -> Understand -> Check + Continue

Lower learning flow

Explore -> Understand -> Check + Continue

Build the core picture before you start testing the idea.

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Lower learning flow

Step 1 of 3Explore

Build the core picture before you start testing the idea.

Current stage

Step 1 of 32 sections

Explore

Build the core picture before you start testing the idea.

What to do here

Start with the explanation and key ideas so the concept has a stable shape before you push on it.

At the bench now

What to notice

Use the prompt surface to decide what to watch in the live bench before you move on.

Why it behaves this way

Explanation

A real source is not just an ideal emf. If the source has internal resistance, some of the emf is lost inside the source itself whenever current flows, so the terminal voltage seen by the load becomes smaller than the emf.

This bench stays intentionally bounded: one source with emf E and internal resistance r drives one load resistance R. That is enough to show why heavy loads pull the terminal voltage down, why the source wastes power internally, and why the ideal-source limit is still useful without pretending every battery is perfect.

Key ideas

01Current depends on the total loop resistance E / (R + r), not on the load resistance alone.

02Terminal voltage is the voltage that actually reaches the load, so under load it is V_terminal = E - I r.

03A larger current means a larger internal voltage drop and more power wasted inside the source.

Bench tools and share links

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Stable links

Progress and next steps

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Progress

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