Page 142 - Physics_Form_2
P. 142
Physics for Secondary Schools
both the order and orientation of the Rotating a mirror
letters are reversed. They are laterally If a mirror is rotated by a certain angle,
inverted. The alphabets that will have what changes can occur to the reflected
the image appear the same as the ray? You know that when light reflects off
alphabet when kept in front of a plane a plane mirror, the angle of incidence is
mirror are A, H, I, M, O, T, U, V, W,
FOR ONLINE READING ONLY
X, and Y. These letters are vertically equal to the angle of reflection. Now, if a
symmetric. That means if we cut the specific angle turns the plane mirror, how
letters in half, both halves will look will this affect the angle of reflection?
similar. There won’t be any change in To explore reflection of ray of light by
appearance when the letter is flipped rotating mirror, perform Activity 4.5.
sideways.
Activity 4.5
Lateral inversion is the phenomenon in
which the image of the object turns 180° Aim: To investigate the reflection
about the vertical axis, such that the right of a ray of light by rotating
side of the object appears as the left side a mirror
of the object and vice versa. For example, Materials: ray box, plane mirror, soft
a card printed with word, REEL when board, protractor, plain
viewed through the mirror the word paper, pins
would appear as ⅃ƎƎЯ.
Procedure
1. Fix a sheet of paper on the soft board
Task 4.4 and draw on it a line L L .
1 2
The following tasks should be done 2. Place a plane mirror vertically with
in pairs. one of its sides along the mirror line
(a) On an index card or sheet of paper, L L to be perpendicular to the soft
2
1
write the word ‘SCHOOL’. Look at board.
the word reflected in a mirror. 3. Introduce a ray of light to strike the
(i) What is the size of the image mirror at a given angle, say 30°.
compared to the object? 4. Mark the paths of the incident ray
(ii) What do you observe about and the reflected ray.
the position of the letters?
(b) Raise your right hand while standing 5. Without moving the ray box, rotate
in front of the mirror. Which hand the mirror slightly through an acute
does your image appear to raise? angle, and mark the new line of the
If a person were facing you, which mirror as L L .
3
4
hand would she raise to look like 6. Mark the path of the incident ray as
your image in the mirror? Present L L and that of the reflected ray as
2
3
your findings to the class members. L L .
3
1
136
Student’s Book Form Two
Physics Form 2 Final.indd 136 25/10/2025 10:27
