A diverging lens has a power of −5.0 D-5.0\ \mathrm{D}−5.0 D. Use P=1f\displaystyle P=\frac{1}{f}P=f1, where f f\,f is in metres. Which gives the focal length and shape of the lens?
−20 cm-20\ \mathrm{cm}−20 cm; thicker at the centre than at the edges
−5.0 cm-5.0\ \mathrm{cm}−5.0 cm; thinner at the centre than at the edges
−20 cm-20\ \mathrm{cm}−20 cm; thinner at the centre than at the edges
−5.0 cm-5.0\ \mathrm{cm}−5.0 cm; thicker at the centre than at the edges
93 exam-style questions on Edexcel GCSE Physics 5.1 Reflection, refraction and lenses, covering 5.1.1 Reflection, refraction and total internal reflection, 5.1.2 Specular and diffuse reflection, 5.1.3 Colour of light: absorption and filters, 5.1.4 Lenses: power, focal length and shape, 5.1.5 Ray diagrams for converging and diverging lenses, and 5.1.6 Real and virtual images. Each one has a worked solution and a mark scheme showing where the marks go.