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Electric circuitsPhysicsHigh schoolabout 0:53

A 24 V source drives 1.2 A through a resistor. What is its resistance?: animated lesson

A narrated, step-by-step electric circuits video lesson with captions. Final answer: resistance R = 20 Ω; P = 28.8 W.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.4 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
A 24 V source drives 1.2 A through a resistor. What is its resistance?
2. Step by step
1. $V = IR$
  Formula: Ohm's law
2. $R = \frac{V}{I}$
  Rearrange for resistance R
3. $R = \frac{(24)}{(1.2)} = 20\ \text{Ω}$
  Substitute the known values
4. $P = VI = 28.8\ \text{W}$
  Power dissipated
3. The answer
$\text{resistance R = 20 Ω; P = 28.8 W}$
resistance R = 20 Ω
4. Check
- Substituted every value back into the formula: both sides agree ✓

Transcript

The problem. Here is the problem: A 24 V source drives 1.2 A through a resistor. What is its resistance? Use the Ohm prime s law formula, rearranged for the unknown, in SI units.

Step by step. Formula: Ohm prime s law. Rearrange for resistance R. Substitute the known values. Power dissipated.

The answer. So the answer is resistance R equals 20 Ω; P equals 28.8 W. Ohm prime s law says the current through a resistor is proportional to the voltage across it: V equals IR. It holds for ohmic conductors such as resistors at constant temperature, not for diodes or filament bulbs over wide ranges.

Check. Substituted every value back into the formula: both sides agree, which checks out.

About electric circuits

Ohm's law, electrical power and resistors in series and parallel.

A 24 V source drives 1.2 A through a resistor. What is its…