A technician is checking a replacement lens for a wildlife camera. The lens has a focal length of +0.40 m. The technician considers these four records.
| Record | Power | Shape |
|---|---|---|
| A | +2.5 D+2.5\ \mathrm{D}+2.5 D | thicker at the centre than at the edges |
| B | +0.40 D+0.40\ \mathrm{D}+0.40 D | thicker at the centre than at the edges |
| C | −2.5 D-2.5\ \mathrm{D}−2.5 D | thinner at the centre than at the edges |
| D | +2.5 D+2.5\ \mathrm{D}+2.5 D | thinner at the centre than at the edges |
Use P=1fP=\dfrac{1}{f}P=f1 to decide which record correctly describes the replacement lens.
Record D
Record A
Record B
Record C
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.