A student investigates the image formed by a converging lens using an optical bench setup.
At the start of the experiment:
(i) On a scale diagram drawn to a scale of one-quarter (14\frac{1}{4}41) full size, the distance ddd on the page representing the distance from the lens to the screen is measured to be 12.0 cm12.0\text{ cm}12.0 cm. Calculate the actual image distance vvv from the lens.
(ii) Use your value of vvv to complete the first row of Table 1.
Table 1:
object distance u / cmimage distance v / cm16.020.030.024.024.036.018.048.016.0\begin{array}{|c|c|} \hline \text{object distance } u \text{ / cm} & \text{image distance } v \text{ / cm} \\ \hline 16.0 & \\ \hline 20.0 & 30.0 \\ \hline 24.0 & 24.0 \\ \hline 36.0 & 18.0 \\ \hline 48.0 & 16.0 \\ \hline \end{array}object distance u / cm16.020.024.036.048.0image distance v / cm30.024.018.016.0(i) State two ways in which the image of the letter 'P' formed on the screen differs from the original illuminated object when u=16.0 cmu = 16.0\text{ cm}u=16.0 cm.
(ii) The magnification mmm of the image is given by:
m=vu m = \frac{v}{u} m=uvCalculate the magnification mmm when u=16.0 cmu = 16.0\text{ cm}u=16.0 cm.
The focal length fff of the lens can be calculated using the equation:
f=uvu+v f = \frac{uv}{u+v} f=u+vuvUse the values from Table 1 for u=24.0 cmu = 24.0\text{ cm}u=24.0 cm to calculate the focal length fff of the lens.
Using the focal length f=12.0 cmf = 12.0\text{ cm}f=12.0 cm, calculate the expected image distance vvv when the object distance is set to u=30.0 cmu = 30.0\text{ cm}u=30.0 cm.
State one technique used during the experiment to ensure that the image on the screen is focused as sharply as possible.
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.