A corrective eyepiece for a telescope uses a diverging lens with a focal length of -12.5 cm.
Calculate the power of this lens in dioptres.
Use the equation:
power of a lens=1focal length in metres \text{power of a lens} = \frac{1}{\text{focal length in metres}} power of a lens=focal length in metres124 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.