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How does a touch screen work?

Touch screens seem to be everywhere. Different systems are in use, but the most versatile uses the physical properties of capacitors. But how is your finger detected?

The terms in bold link to topics in the AQA, Edexcel, OCR, WJEC and CCEA A-level specifications, as well as the IB, Pre-U and SQA exam specifications.

A charged capacitor has an associated electric field. A nearby finger reduces the electric field strength, which increases the capacitance. This increases the stored charge, allowing the finger to be detected.

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Earth’s electric atmosphere

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Stars, spheres and spectra

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