IGCSE Light Lesson Hub

P3.2.1 Core 1

Use ray diagrams to define the terms normal, angle of incidence and angle of reflection

Question 1

In reflection diagrams, the normal is:

a line parallel to the mirrora line drawn perpendicular to the surface at the point of incidencethe reflected raythe angle between the mirror and the incident ray

Question 2

The angle of incidence is measured between:

the incident ray and the mirror surfacethe incident ray and the normalthe reflected ray and the mirrorthe incident ray and the reflected ray

Question 3

The angle of reflection is measured between:

the reflected ray and the normalthe reflected ray and the mirror surfacethe incident ray and the mirror surfacethe object and the mirror

Question 4

Which part of a ray diagram is usually drawn as a dashed line?

the mirrorthe normalthe objectthe reflected ray

Question 5

A ray strikes a plane mirror. Which quantity is needed first to identify the angle of reflection correctly?

the distance to the objectthe normal linethe thickness of the mirrorthe speed of light

P3.2.1 Core 2

Describe the formation of an optical image by a vertical plane mirror and give its characteristics

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Question 6

An image in a plane mirror is:

larger than the objectsmaller than the objectthe same size as the objectupside down

Question 7

The image in a plane mirror is found:

behind the mirroron the mirror surfacein front of the mirrorinside the glass only

Question 8

If an object is 2 m in front of a plane mirror, the image appears:

1 m behind the mirror2 m behind the mirror4 m behind the mirror2 m in front of the mirror

Question 9

Which phrase describes a plane mirror image correctly?

real and invertedvirtual and uprightreal and magnifiedvirtual and upside down

Question 10

Lateral inversion means the image is:

upside downleft-right reversedsmallerblurred

P3.2.1 Core 3

State that for reflection, the angle of incidence is equal to the angle of reflection; recall and use this relation

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Question 11

A ray strikes a mirror with an angle of incidence of 35°. The angle of reflection is:

35°55°70°145°

Question 12

The law of reflection states that:

i = ri + r = 90°i is always greater than rreflected rays bend toward the normal

Question 13

If the incident angle is measured from the mirror surface as 20°, what is the angle of incidence from the normal?

20°70°90°110°

Question 14

Which statement is true for a plane mirror?

The reflected ray always passes through the mirrorThe incident and reflected rays lie in the same planeThe reflected ray is always weakerThe angle of reflection is measured from the surface

Question 15

If angle of reflection is 48°, the angle between incident and reflected rays is:

24°48°96°132°

P3.2.1 Supplement 4

Describe the formation of an optical image by a plane mirror and explain why it is virtual

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Question 16

A plane mirror image is virtual because:

light actually passes through the imagethe rays only appear to come from behind the mirrorthe image can be projected onto a screenthe mirror produces no reflection

Question 17

To locate a virtual image in a ray diagram, you usually:

draw actual rays behind the mirrorextend reflected rays backward as dotted linesignore the reflected raysmeasure from the object only

Question 18

Which one is NOT a property of a plane mirror image?

uprightvirtualsame sizeformed on a screen

Question 19

Why can the eye still see a virtual image?

The eye traces the reflected rays back in straight linesThe image produces its own lightThe mirror bends light around cornersThe eye receives no reflected light

Question 20

Which diagram feature best shows that an image is virtual?

solid rays meeting in front of the mirrordashed lines meeting behind the mirrora thicker mirrora curved normal

P3.2.1 Supplement 5

Use simple diagrams, measurements and calculations for reflection by plane mirrors

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Question 21

An object is 5 cm from a plane mirror. How far is the image from the mirror?

2.5 cm5 cm10 cm15 cm

Question 22

The distance between an object and its plane mirror image is 12 cm. The object is how far from the mirror?

3 cm6 cm12 cm24 cm

Question 23

If the angle between the incident ray and the normal is 62°, the reflected angle is:

28°31°62°124°

Question 24

A student measures the angle from the mirror surface instead of the normal. This value will be:

the same as the angle of reflectioncomplementary to the correct anglealways larger than 90°always zero

Question 25

For a vertical plane mirror, the minimum information needed to draw the reflected ray accurately is:

the object height onlythe point of incidence and the normalthe image size onlythe thickness of the mirror

P3.2.2 Core 1

Define refraction as the change in direction of a light ray passing from one medium to another

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Question 26

Refraction is best defined as:

reflection from a shiny surfacethe change in direction of light when it passes from one medium to anotherthe absorption of lightthe splitting of white light

Question 27

Light usually refracts because its:

colour changes onlyspeed changes in the new mediummass changesfrequency becomes zero

Question 28

If a ray passes straight along the normal into a new medium, it will:

bend away from the normalbend toward the normalcontinue undeviatedreflect completely

Question 29

Which pair names two different media?

glass and glassair and watermirror and mirrorvacuum and vacuum

Question 30

When light enters glass from air, the path usually:

remains unchanged in every casebends because the speed changesstops completelyturns into sound

P3.2.2 Core 2

Define and use the terms normal, angle of incidence and angle of refraction using ray diagrams

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Question 31

In a refraction diagram, the angle of refraction is measured between:

the refracted ray and the surfacethe refracted ray and the normalthe incident ray and the surfacethe refracted ray and the reflected ray

Question 32

The normal at the boundary is drawn:

parallel to the surfaceperpendicular to the surfacealong the incident raythrough the image only

Question 33

The angle of incidence is the angle between:

the incident ray and the normalthe incident ray and the surfacethe refracted ray and the surfacethe object and the boundary

Question 34

A student labels the angle between the refracted ray and the surface as r. This is:

correctincorrect because r should be measured from the normalalways 0°the refractive index

Question 35

Which one should appear in a basic refraction ray diagram?

a normal linea focal pointa lens formulaa magnetic field line

P3.2.2 Core 3

Describe the passage of light through a transparent material (limited to the boundaries between two media only)

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Question 36

When light passes from air into glass, it usually bends:

toward the normalaway from the normalinto a circlenot at all

Question 37

When light leaves glass and enters air, it usually bends:

toward the normalaway from the normalinto the mirrorback to the source only

Question 38

A transparent block with parallel sides causes the emerging ray to be:

parallel to the incident rayat 90° to the incident rayalways reflected backunable to leave the block

Question 39

Which statement is true about a ray traveling from one transparent medium to another?

It must always reflect fullyIt may change direction at the boundaryIt loses all energyIt stops at the surface

Question 40

Which material is transparent to visible light?

woodclear glasscardboardbrick

P3.2.2 Supplement 4

Define refractive index, n, as the ratio of the speeds of a wave in two different regions

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Question 41

Refractive index compares:

mass and weightwave speeds in two mediacurrent and voltagedistance and time only

Question 42

If light travels slower in glass than in air, the refractive index of glass relative to air is usually:

less than 1equal to 1greater than 1zero

Question 43

A larger refractive index usually means light is traveling:

faster in that mediumslower in that mediumwith no change in speedbackward

Question 44

If n = speed in air / speed in glass, and light is slower in glass, n will be:

negativegreater than 1equal to 0less than 1

Question 45

Which quantity is not directly used in the speed definition of refractive index?

speed in one mediumspeed in another mediumratiotemperature of the Sun

P3.2.2 Supplement 5

Recall and use the equation n = sin i / sin r

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Question 46

Which equation is used for refractive index in this objective?

n = i/rn = sin i / sin rn = sin r / sin in = i + r

Question 47

If i = 30° and r = 20°, n is closest to:

0.681.001.462.50

Question 48

If n = 1.5 and i = 45°, which expression gives sin r?

sin r = 1.5 sin 45°sin r = sin 45° / 1.5sin r = 45 / 1.5sin r = 1.5 / 45

Question 49

In the equation n = sin i / sin r, i and r are measured from:

the surfacethe normalthe objectthe screen

Question 50

For light entering glass from air, which is usually true?

r > ir = i alwaysr < ir = 90°

P3.2 Reflection and Refraction

Use ray diagrams to define the terms normal, angle of incidence and angle of reflection

Describe the formation of an optical image by a vertical plane mirror and give its characteristics

State that for reflection, the angle of incidence is equal to the angle of reflection; recall and use this relation

Describe the formation of an optical image by a plane mirror and explain why it is virtual

Use simple diagrams, measurements and calculations for reflection by plane mirrors

Define refraction as the change in direction of a light ray passing from one medium to another

Define and use the terms normal, angle of incidence and angle of refraction using ray diagrams

Describe the passage of light through a transparent material (limited to the boundaries between two media only)

Define refractive index, n, as the ratio of the speeds of a wave in two different regions

Recall and use the equation n = sin i / sin r