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1
29 exceeds28.
Class 7 · English Version · General science
Forces, energy and electricity
Explain a feedback system and distinguish sensing from action.
Original Kidemy further-topic investigation. This optional lesson is shared by related upper pathways; select suitable depth with a teacher. It does not certify complete grade or board coverage.
Learn the idea
A feedback system measures a quantity, compares it with a target and acts to reduce a difference. A sensor alone does not change the environment. Real systems can respond slowly or overshoot, so repeated observation matters.
Worked example
A fictional greenhouse controller switches a fan on above28 °C and off below26 °C. The gap between thresholds prevents rapid switching around one temperature. This is a paper model, not wiring guidance.
- Define target and thresholds.
- Trace input, stored state and action.
- Explain a delay or alternative cause.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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0
25 is below26.
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temperature sensor
The sensor supplies the measurement.
Write in your own words. A guardian or teacher should review this response.
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The fan keeps its previous state because neither switching threshold is crossed.
Use state and both thresholds.
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The reading may change for other reasons and the fan action needs a comparable observation.
Separate sensing, action and evidence.
Apply the idea
Draw an input–comparison–action loop and trace five temperatures through it.
Review with a guardian or teacher
- Use the stated evidence or givens.
- Show reasoning rather than only a result.
- Review and explain one correction.
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