A student is performing an experiment using a thin converging lens to find its focal length. They are provided with:
Describe the correct order and alignment of the illuminated object, the lens, and the screen along the bench to perform this experiment.
The focal length of the lens is approximately 20 cm20\text{ cm}20 cm. Suggest a suitable distance ddd between the illuminated object and the screen so that a sharp image can be focused on the screen, and explain your choice with reference to the focal length fff.
State two practical difficulties in this experiment that make it hard to obtain an accurate value for the focal length.
Describe the appearance of the focused image of the capital letter F as seen on the screen by the student.
216 exam-style questions on CIE IGCSE Physics 3.2 Light, covering 3.2.1a Reflection of light, 3.2.1b Images in a plane mirror, 3.2.2 Refraction of light, 3.2.2a Refraction of light, 3.2.2b Total internal reflection, 3.2.2c Refractive index and critical angle, 3.2.2d Optical fibres, 3.2.3a Converging and diverging lenses, 3.2.3b Ray diagrams and the nature of images, 3.2.3c Virtual images and the magnifying glass, 3.2.3d Correcting long-sightedness and short-sightedness, and 3.2.4 Dispersion of light. Each one has a worked solution and a mark scheme showing where the marks go.