This thicker-centred lens converges parallel rays of light in air.

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Your new ahaConvex lens

A convex lens can bring parallel rays to a focus. Source: Convex lens ↗

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45This thinner-centred lens spreads parallel rays of light in air.RECALL
Concave lens
It is thinner in the middle
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46This wave behaviour produces spreading around obstacles or through openings.RECALL
Diffraction
It is strongest when the gap is comparable to the wavelength
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47SI unit of electric currentRECALL
ampere (A)
One of seven SI base units
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