Resistance — Science definition

Defined in 3 courses:

Anything that opposes the flow of current, measured in ohms (Ω). (Physical Science: Matter, Forces & Energy)
The degree to which a system remains similar during a disturbance. (Life Science: Biology)
The opposition a material offers to the flow of current, measured in ohms (Ω). (Physics & Environmental Science)

Where it is taught

Electricity & Simple Circuits — Energy & Heat Transfer, Physical Science: Matter, Forces & Energy, Grade 8
Disturbance, Interactions & Ecosystem Change — Ecosystems & Conservation Decisions, Life Science: Biology, Grade 10
Current, Voltage & Resistance — Electricity, Magnetism & Circuits, Physics & Environmental Science, Grade 12

In use

Resistance, measured in ohms (Ω), is anything that opposes or slows that flow.
Electricity & Simple Circuits

Resistance describes how little a system changes; recovery describes its return after a disturbance.
Disturbance, Interactions & Ecosystem Change

The third member of the trio is resistance, the opposition a material offers to the flow of charge, measured in ohms (Ω).
Current, Voltage & Resistance

Questions using resistance

Problem 1

A circuit has 9 volts and 3 ohms of resistance. Find the current.

Answer and explanation

3 A

I = V ÷ R = 9 ÷ 3 = 3 A.

Problem 2

A 15-volt circuit has a current of 5 amps. Find the resistance.

Answer and explanation

3 Ω

R = V ÷ I = 15 ÷ 5 = 3 Ω.

Problem 3

A 9 V supply drives 0.3 A. What is the resistance in ohms?

Answer and explanation

30 Ω

R = V/I = 9/0.3 = 30 Ω.

Problem 4

Original resistance/recovery comparison with arbitrary output indices, not complete ecosystem restoration evidence.

Interpret the supplied visual. Which supplied model has lower resistance but faster recovery?

Answer and explanation

A changes from 100 to 20, then returns to 100 by year four; B changes less but has not returned in that interval.

Resistance describes how little a system changes during a specified disturbance. Recovery describes return of selected properties afterward. Resilience is used in several related ways, so define the sense and measured variable before comparing systems. A system can change strongly yet recover rapidly, while another changes little but recovers slowly. Returning one output to baseline does not guarantee identical species composition or restored every function. Compare reference variability and the time interval rather than rank ecosystems by one undefined resilience label.

A changes from 100 to 20, then returns to 100 by year four; B changes less but has not returned in that interval.

Response criteria

Read the structures, axes, directions and units correctly.
Connect the evidence with the biological mechanism.
Respect stated model assumptions and distinguish an observation from a further inference.

Taught alongside

Elsewhere

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