Priya designed an experiment to investigate what light does when it falls on different surfaces. She used a special red lamp to shine a light on different surfaces. Priya wrote down these results in a table. Surface Reflected light seen Any other observations Metal painted matte black None (black) After a few minutes, the metal felt warm to the touch. Polished metal (shiny silver) Red light After a few minutes, there was no change in temperature of the metal. Metal polished with a green plastic layer on top None (black) After a few minutes the metal temperature did not appear to change.

The process of sending back light rays which fall on the surface of an object is called the reflection of light. In the first case, Priya shines a metal painted matte which is black with a red lamp. Objects appear black when they do not reflect any light at all. We say that a black object absorbs all the light that shines on it. The effect is called absorption. Here, the red light is absorbed by the black matte, and we cannot see any reflected light. We know that black coloured materials absorb and radiate heat at the fastest rate. Here, the absorbed light energy is converted into heat energy and after a few minutes, the metal felt warm to the touch. In the second case, when red light falls on polished metal, the reflected light will also be red as a polished metal will reflect the same colour of light that falls on it. Here, all the red light that falls on the polished metal surface is reflected and therefore no change in temperature takes place. In the third case, red light falls on a metal that is polished with a green plastic layer on top. Here, it absorbs the red colour of light and no reflection of light happens, as a green colour surface cannot reflect red light. Hence, the reflected light will appear black. Since the green colour does not have good absorbing power as black, it will not radiate heat as black colour does. So after a few minutes, the metal temperature did not appear to change.

E M B I B E

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 7 - Light>Exercise 4

Aidan Gill, Heidi Foxford and, Dorothy Warren Solutions for Chapter: Light, Exercise 4: Exercise 4

Author:Aidan Gill, Heidi Foxford & Dorothy Warren

Aidan Gill Science Solutions for Exercise - Aidan Gill, Heidi Foxford and, Dorothy Warren Solutions for Chapter: Light, Exercise 4: Exercise 4

Attempt the free practice questions on Chapter 7: Light, Exercise 4: Exercise 4 with hints and solutions to strengthen your understanding. Cambridge Lower Secondary Science Stage 8 : Workbook solutions are prepared by Experienced Embibe Experts.

Questions from Aidan Gill, Heidi Foxford and, Dorothy Warren Solutions for Chapter: Light, Exercise 4: Exercise 4 with Hints & Solutions

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 7 - Light>Exercise 4>Q 3

The diagram shows three large coloured lamps arranged one above the other. They shine through a thick glass block onto a screen.
The orange light ray shown hits the block at a right-angle. Complete the ray diagram for the orange light. Label the point on the screen where the ray arrives with the letter 'X'.

Question Image

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 7 - Light>Exercise 4>Q 3

The diagram shows three large coloured lamps arranged one above the other. They shine through a thick glass block onto a screen.
The orange light ray shown hits the block at a right-angle. Complete the ray diagram for the orange light. Label the point on the screen where the ray arrives with the letter 'X'.

Question Image

Add rays for the red and green lamps to show rays that also arrive at point 'X'.

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 7 - Light>Exercise 4>Q 5

Look at the diagram showing different surfaces. Predict what will be observed when light falls on each surface. Complete the table with your answers.

Question Image

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 7 - Light>Exercise 4>Q 6

Priya designed an experiment to investigate what light does when it falls on different surfaces. She used a special red lamp to shine a light on different surfaces. Priya wrote down these results in a table.

Surface	Reflected light seen	Any other observations
Metal painted matte black	None (black)	After a few minutes, the metal felt warm to the touch.
Polished metal (shiny silver)	Red light	After a few minutes, there was no change in temperature of the metal.
Metal polished with a green plastic layer on top	None (black)	After a few minutes the metal temperature did not appear to change.

Learn and Prepare for any exam you want !

|

|

|

|

|

|

|

|