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Electric circuitsPhysicsHigh schoolabout 0:52

Resistors of 100, 25 Ω are connected in parallel across 10 V. Find the equivalent resistance and total current: animated lesson

A narrated, step-by-step electric circuits video lesson with captions. Final answer: R_T = 20 Ω; I = 0.5 A, P = 5 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
Resistors of 100, 25 Ω are connected in parallel across 10 V. Find the equivalent resistance and total current.
2. Step by step
1. $\frac{1}{R_T} = \frac{1}{100} + \frac{1}{25} = \frac{1}{20}\ \Rightarrow\ R_T = 20\ \Omega$
  Parallel: reciprocals add
2. $I = \frac{V}{R_T} = \frac{10}{20} = 0.5\ \text{A}$
  Total current from Ohm's law
3. $I_{1} = 0.1\ \text{A},\ I_{2} = 0.4\ \text{A}$
  Current in each branch (same voltage)
4. $P = VI = 5\ \text{W}$
  Power delivered
3. The answer
$\text{R\_T = 20 Ω; I = 0.5 A, P = 5 W}$
R_T = 20 Ω; I = 0.5 A, P = 5 W
4. Check
- R_T ≤ every individual resistor ✓

Transcript

The problem. Here is the problem: Resistors of 100, 25 Ω are connected in parallel across 10 V. Find the equivalent resistance and total current. Resistors in parallel share the same voltage; their conductances (1/R) add.

Step by step. Parallel: reciprocals add. Total current from Ohm prime s law. Current in each branch (same voltage). The branch currents add up to the total current. Power delivered.

The answer. So the answer is R T equals 20 Ω; I equals 0.5 A, P equals 5 W. The equivalent resistance of a parallel network is always smaller than its smallest resistor; two equal resistors in parallel give half of one.

Check. R T less than or equal to every individual resistor, which checks out.

About electric circuits

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

Resistors of 100, 25 Ω are connected in parallel across 10…