Revison on Light (P4)

1. The diagram below shows a bent tube with 7 mirrors.

                                

Which of the following items will Susan be able to see?

           

A: Heart                                                          

B: Square                                           

C: Triangle

D: Crescent

(1)        B only                                                 

(2)        A and B only                                      

(3)        C and D only

(4)        A, C and D only                                                                                  (           )

White screen

Light source

2.         Study the set up as shown below.

                       

                       

Object A

Object B

Object C

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                Objects A, B and C were placed between the light source and white screen one at a           time.

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

Object A

Object B

Object C

The following observations were made.

Which of the following explains why the above observations were made?

A:         Light is reflected.

B:         Object B is opaque while Object A is transparent.

C:        Object C is placed furthest away from the light source.

D:        The path of light is blocked by at least one of the objects.

(1)        A and B only

(2)        B and D only

(3)        A, C and D only

(4)        B, C and D only                                                                                  (          )

3.         An experiment was carried out in a dark room. Four sheets, W, X, Y and Z, of       different materials were arranged in a straight line as shown below. When the torch  was switched on, a bright patch of light was seen on Sheet Y only.

            Which one of the following is true?

           

                                                                                                                        (           )

Section B: OPEN ENDED (2 X 2 = 4 marks)

4.            The set-up below shows light from a torch shining on three cardboard shapes        arranged at different distances from the torch, in positions 1, 2 and 3.

screen

 The diagram below shows the shadow that was formed on the screen.

The shapes of the three cardboards used are shown in the diagrams below.

(a)  List the possible arrangements of the three cardboard shapes that formed the shadow on the screen, with position 1 being the shape that is closest to the torch and position 3 being the shape furthest from the torch. [1m]

Position 1: _________________________________

Position 2: __________________________________

Position 3: ___________________________________

(b)  Explain how the shadow on the screen could be formed even though the three cardboard shapes used were of the same height. [1m]

______________________________________________________________________________________________________________________________________________________

5.         Reyan wanted to find out about which type of paint J, K, L and M reflects the most           light. He painted four similar pieces of wood with the same colour but of different     types of paint. The diagram below shows the set-up that he used for his investigation.

                   

 

a)         In the diagram above, in which position (A, B, C or D) should Reyan place the light            sensor to measure the light reflected by the paint? [1m]

            ___________________________________________________________________

b)         Explain why the experiment has to be conducted in a dark room. [1m]

            ___________________________________________________________________

            ___________________________________________________________________

Answer Key

Qns.	Answer
(1)	1
(2)	2
(3)	4

4a)      Position 1: hollow triangle             (award 1m for all 3 correct positions)

Position 2: rectangle

Position 3: circle

b)         As the hollow triangle is the nearest/closest to the torch, it will form the largest shadow (1/2m), and since the circle is the furthest from the torch, it will form the smallest shadow (1/2m).

5a)       Position A. [1m]

b)         This is to ensure that the light sensor only measures light reflected from the wood. [1m]

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