HALF QUESTION Typical of Question 12 in Leaving Cert. Exam
Q3 Answer both of the following parts (a) and (b). (a) State the laws of reflection of light. (6)
A concave mirror has a focal length of 30 cm.An object is placed 45 cm in front of the mirror. How far from the mirror will the image be formed? (9)
Using the same concave mirror, find the two positions at which an object may be placed so that the image formed may be twice the size of the object. (13)
(b) What is meant by the reflection of light? (6)
Describe an experiment to demonstrate one of the laws of reflection of light. (12)
A student found the focal length of a concave mirror using the apparatus illustrated in Fig 12.19.
By adjusting the distance from the pin to the centre of curvature of the mirror a position of no parallax was found between the pin and its image in the mirror.The distance at which this occurred was 20 cm from the pole of the mirror.What was the focal length of the mirror? Use a ray diagram to justify this answer. (10)