Question
(a) Fig. 9.1 shows two rays of light X and Y leaving an object O. The rays strike a plane mirror. Ray X is reflected as shown.
(i) On Fig. 9.1, draw the normal at the point where ray X strikes the mirror.
(ii) On Fig. 9.1, draw the path of ray Y after it strikes the mirror.
(b) An object O is placed on the left of a thin converging lens. F is the principal focus.
This arrangement is shown in Fig. 9.2.
Two rays from the top of the object are incident on the lens, as shown in Fig. 9.2.
On Fig. 9.2, draw the path of each ray to locate the position of the image of O formed by the lens.
On Fig. 9.2, draw an arrow to represent the image and label it I.
Answer/Explanation
Answer:
(a)
(i) normal at X correct by eye
(ii) reflected ray for Y has angle r by eye
(b) horizontal ray drawn to continue through F
ray to centre drawn to continue undeviated
image drawn correctly where rays cross
Question
Fig. 7.1 shows the principal axis PQ of a converging lens and the centre line XY of the lens.
An object 2.0 cm high is placed 2.0 cm to the left of the lens. The converging lens has a focal length of 3.0 cm.
(a) On Fig. 7.1, draw a full-scale diagram to find the distance of the image from the lens, and the height of the image. distance of image from the lens =………………………………………………
height of image = ………………………………………………
(b) State and explain whether the image in (a) is real or virtual………………………………………………………………………………………………………………………….
……………………………………………………………………………………………………………………..
Answer/Explanation
Answer:
(a) two of: ray through centre of lens undeviated ray parallel to axis refracted to right hand focus rays through left hand focus refracted parallel to axis rays extrapolated to a point accuracy marks: image 6 cm from lens image 6 cm high
(b) image is virtual/not real AND cannot be seen on screen OR no rays come from (position of) image