5.1 Understanding
reflection of
light. / A student is able to:
5.1.1Describe the characteristic of the image formed by reflection of light
5.1.2State the laws of reflection of light
5.1.3Draw ray diagrams to show the position and characteristics of the
image formed by aplane mirror, convex mirror and concave mirror
5.1.4Describe applications of reflection of light
5.1.5Solve problems involving reflection of light
5.1.6Construct a device based on the application of reflection of light

CHAPTER 5

LIGHT

Learning Objective and Learning Outcomes

( …………. / 22 X 100% = ………………. % )

Fill in the blanks with the suitable terms:

  1. The characteristics of image when light from an object is reflected by a plane mirror includes

,same size, from the mirror at perpendicular line and virtual.

2. The Law of reflection of light states that

i) the angle of incidence equals

ii) the incident ray, the reflected ray and are all lie at the same plane

3. (a) Complete the image of L in the diagram of reflection below.

(b) On the diagram above,

  1. Show the light ray direction and the normal line of the mirror,
  2. show the angle of incidence and label as i, the angle of reflection and label as r
  3. show the distance of object, lo and distance of image li perpendicular to the mirror
  1. When the parallel rays are directed to concave mirror, the reflected rays will meet at a point

the mirror. It is called the of the concave mirror.

5. When the parallel rays are directed to convex mirror, the reflected rays will . When the

rays are extrapolated, it will meet at a point the mirror, it’s the .

6.Diagram below shows three parallel rays are directed to a concave and a convex lens, draw the

reflected rays and indicate the focal point, F in each case. Show the direction of reflected rays.

Relate the relation between centre of curvature, C, with focal point, F, of a mirror.

7. Convex mirror is often installed at the cornering of a hidden road and in the convenience store.

This mirror allows us to see angle of objects but the size of the image is

8. Diagram below shows a ray directed on a plane mirror.

i) Uses a red / blue ink ball pen, draw the normal line and the reflected ray for the given incident

ray (use protractor and ruler to assist you).

ii) Now, using a pencil draw to show the mirror turned 10o clockwise. Thus, draw the new

normal line and new reflected ray. Observe the changes of angle for the reflected ray.

9. When a mirror turns xo, the angle between the two rays (incident and reflected) will have a

change of

10.Mirror is used in measuring instruments like ammeter, voltmeter and galvanometer. It is to help

the user to read accurately and avoid ______

Learning Objective and Learning Outcomes

5.2 Understanding
refraction of
light. / A student is able to:
5.2.1Explain refraction of light
5.2.2Define refractive index as
5.2.3Determine the refractive index of a glass or Perspex block
5.2.4State the refractive index, ,
as Speed of light in a vacuum
Speed of light in a medium
5.2.5Describe phenomena due to refraction
5.2.6Solve problems involving refraction of light

( …………. / 24 X 100% = ………………. % )

  1. Light travels in a straight line, but when travels from one medium to another medium with different , it changes direction. The change in direction when light ray travels from one medium to another medium is called refraction .
  1. The light ray that travels along the normal line of the boundary between two medium does not bend.
  1. When a light ray travels from an optically denser medium to a less dense medium, it refracts far from the normal.
  1. When a light ray travels from an optically less dense medium to a denser medium, the angle of incident ray (at less dense medium) is larger then the angle of refracted ray (at denser medium).
  1. In the diagram below,
  2. draw two normal lines of the ray to and from the glass block
  3. show the refracted light of the glass block
  4. complete the direction of light
  5. indicate the angle of incident, , and the angle of refraction, .
  1. Angle of incident or angle of refraction is an angle made between the ray and the

normal line.

  1. Snell’s Law says that the ratio of is a constant. It is known as the

refractive index of a medium (water / glass / perspex), n, where .

  1. The speed of light decreases as it travel into a medium, therefore the refractive index of a medium n = , simplified n = .
  1. Due to refraction of light,
  2. a straight straw / rod appears bent at the boundary of liquid.
  1. the bottom of a pool liquid appears shallower / nearer to the surface that it actually is.
  1. The refractive index of liquid can be calculated using, n = , simplified n =.
  1. In the diagram below use the following steps to construct the refraction of light of a coin in a beaker of water.
  1. draw the two normal lines at the boundary of liquid
  2. draw and show the two rays refracted at the air (further from normal line)
  3. draw an eye at the correct position
  4. from the eye, followed the refracted rays, extra-polated dotted lines backward and meet

above the original coin. Draw a dotted oval shape,

to represents the image of the coin.

  1. The phenomenon of refraction of light include mirage, sunrise, sunset, twinkling stars at

night and wriggling of distant objects on hot day.

Learning Objective and Learning Outcomes

5.3 Understanding
total internal
reflection of
light. / A student is able to:
5.3.1Explain total internal reflection of light
5.3.2Define critical angle (c)
5.3.3Relate the critical angle to the refractive index i.e
5.3.4Describe natural phenomenon involving total internal reflection
5.3.5Describe applications of total internal reflection
5.3.6Solve problems involving total internal reflection

( …………. / 25 X 100% = ………………. % )

1. Diagram below shows a light ray travels through a semicircle glass block. If the angle,

of incident is small, most of the light is refracted butsome is reflected.

Label in the diagram i) the refracted light and reflected light

ii) the angle of incident, and angle of refraction, r.

2. The critical angle, c is the incident angle, when the maximum refraction occurs at r = 90 o.

On the diagram below, label the critical angle, c and refraction angle, r.

3. The total internal reflection occurs when,

(a) i) light travels from a denser medium to a less dense medium and

ii) when the incidentangle,is greater than the critical angle, c

(b) name the phenomena occurs in the diagram below.

4. Another formula of refractive index, n =

5. The phenomenon of total refraction of lights includes

a) mirage in the desert

b) mirage on hot afternoon on highway

c) rainbow

6. The phenomenon of mirage occurs is due to the different layers of hot air, hot air on the ground is less dense compare with cold air at higher level on hot day. The water droplets from the cloud are refracted further and further from the normal line. When the angle of incident ray is large enough , it created a total internal reflection on the ground level. Our eye sight sees straight as though there are water drops on the ground.

7. Refers to the diagram given below:

i) In each of the box fill in two of the following characteristics of air:

hot air, colder air, denser, less dense,ray (closer to / further) from normal line

ii) Complete the ray diagram of mirage starts from the object.

iii) Show how we can see the pool of water (mirage) on the highway.

Learning Objective and Learning Outcomes

5.4 Understanding
lenses. / A student is able to:
5.4.1Explain focal point and focal length
5.4.2Determine the focal point and focal length of a convex lens and concave lens
5.4.3Draw ray diagrams to show the positions and characteristics of the images formed by a convex lens and concave lens.
5.4.4Define magnification as
5.4.5Relate focal length (f) to the object distance (u) and image distance (v) i.e.
5.4.6Describe, with the aid of ray diagrams, the use of lenses in optical devices.
5.4.7Construct an optical device that uses lenses.
5.4.8Solve problems involving to lenses.

( …………. / 32 X 100% = ………………. % )

  1. When light passes through a convex lens, the light converges to a point and we call it

focal point. Convex lens is also known as a converging lens.

  1. Concave lens is also known as a diverging lens because light passes through it diverge from a point, the focal point, F.
  2. For the ray diagram below fill in the following labels:

Principle axis, P, Optical centre, O, Focal point, F, focal length, f

  1. Complete the following ray diagrams to find out the images of each one.

Given the characteristics of images includes real or virtual, upright or inverted,

diminished / smaller, same or magnified or larger. State the characteristics for each.

a)

b)

c)

  1. (a) When the object is too near from the convex lens, the image is virtual, magnified and upright.

(b) Concave lens produce only one type of image that is virtual, diminished and upright.

Base on the two statements above, draw the images for the following diagrams.

(i) (ii)

  1. Complete the following ray diagram and name the characteristics for each.
  1. The symbol for image distance is and the symbol for object distance is .
  2. The formula for magnification m = or m =
  3. Given the formula can be used to solve optical problems. Explain what does it means when f is negative value, f is positive value, v is negative value and v is positive value.

f is negative : …………………………………………………………………………………….

f is positive : …………………………………………………………………………………….

v is negative : ……………………………………………………………………………………

v is positive : …………………………………………………………………………………….

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