DOWEN COLLEGE LAGOS
PHYSICS SS2
ASSGNMENT 2
TOPIC : LIGHT:
Light is a form of wave motion and shows some kinds of behaviour as other waves, In essence light
shows some basic characteristics of waves.
RAYS AND BEAMS OF LIGHT
RAYS: a ray of light refers to a narrow stream of light energy, In essence it is the direction or path
taken by light to travel from one point to another , Rays are represented by a straight line with an
arrow showing the direction to which the ray is travelling.
BEAM: A collection of ray is called beam. There are three types of beam
a)
parallel beam
b)
convergent beam
c)
divergent beam
DEFINITION OF TERMS
1)
LUMINIOUS OBJECT: These are objects that can produce light on their own accord eg, sun,
light insect etc
2)
NON –LUMINOUS OBJECTS: These are objects that cannot produce light on their own
accord, e.g candle, lantern, electric bulb etc
3)
OPAQUE OBJECTS:
These are objects that cannot allow rays of light to pass trhough e.g,
wood, plastic, iron , wall, etc
4)
TRANSPARENT OBJECT: These are objects that allow rays of light to pass through, e.g
transparent glass, transparent plastics etc
5)
TRANSLUSCENT OBJECTS: These are objects that can only some degree of light intendity to
pass through , these object will only allow some rays of light to go through faintly, e.g tracing
paper, paper soaked with oil. Etc.
RECTILINEAR PROPAGATION OF LIGHT
This statement means that light travel on a straight line, various experiment can be used to show
this,
Experiment to show this can be found in your textbook, do a personal reading on it,
SHADOWS:
Shadows are formed when an opaque object obstruct the ray of light, generally there are two
regions for every shadow, the region of total darkness call umbra and the region of partial darkness
call penumbra.
ECLIPSES: There are two major types of eclipses
1
)ECLIPSE OF THE SUN(SOLAR ECLIPSE): When the moon passes between the sun and the
Earth, and all the three are in a straight line such that the shadow of the moon falls on the
Earth, hence we have eclipse of the Sun.
2)
ECLIPSE OF THE MOON LUNAR ECLIPSE: This occurs when the Earth passes between the sun
and the moon and all the three are arranged in a straight line, this is call eclipse of the moon
or lunar eclipse.
ASSIGNMENT 2
Answer all the questions
1
2
Explain the following and give two examples in each case
(a)
luminous Objects
(b)
Non luminous Objects
(c)
Opaque objects
(d)
Transparent object
(e)
Translucent objects
Differentiate between a ray of light and a beam of light, diagram are very essential
3
Using ray diagrams only give the three types of beam.
4
Describe an experiment to show that light travels on a straight line.
5
Explain briefly the two types of eclipses mentioned. Diagrams are very essential.
(20 marks)
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