Chapter 2  (Reflection )

1. Regarding reflection:

a. it always occurs when light travels from one medium into another

b. the incident ray and the reflected lie in the same plane

c. the angle of incidence is always equals to the angle of reflection

d. diffuse reflection occurs when light is reflected from a regular surface

e. catoptric images are images reflected from the surfaces of the eye
 

Answera.T   b.T  c.T    d.F   e.T
Reflection always occurs (to a large or small extent) when a light travels 
from one medium into another. According to the laws of reflection: the incident ray and the reflected ray lie in the same plane and the angle of incidence is always equals to the angle of reflection. 
Diffuse reflection occurs when light is reflected from an irregular surface. Catoptric images are images reflected from the surfaces of the eye.
 
 

2. The image of an object formed by reflection at a plane surface 
     has the following properties:

a. the image is upright

b. the image is laterally inverted 

c. the image is real

d. it is located along a line perpendicular to the reflecting surface

e. it is as far behind the surface as the object is in front of it.
 

Answera.T  b.T  c.F  d.T  e.T
The image of an object formed by reflection at a plane surface is upright, 
laterally inverted and virtual. It is located along a line perpendicular to the reflecting surface and is as far behind the surface as the object is in front of it.
 
 

3. The following are true about reflection on a mirror:

a. the focal length of a concave mirror is half the length of its radius 
    of curvature

b. the focal length of a convex mirror is half the length of the its radius 
    of curvature

c. the image formed by a concave mirror is always magnified

d. the image formed by a convex mirror is always magnified

e. the shorter the radius of curvature of a spherical mirror, the stronger
    its refractive power.
 

Answer
a.T   b.T  c.F  d.F  e.F
The focal length of a spherical mirror be it convex or concave is half the 
length of its radius of curvature. As the power of a spherical mirror is 2/r 
where r is the radius of curvature, the shorter the radius of curvature of a spherical mirror the stronger its refractive power. The image formed by a concave mirror is always minified, the image formed by a convex mirror may be magnified or minified depending on the position of the object.
 

4. For an object situated between the centre of curvature and the principal focus 
    of a concave mirror, the image has the following characteristics:

a. it is erect

b. it is virtual

c. it is real 

d. it is magnified

e. the image is found within the centre of curvature
 

Answer
a.F   b.F  c.T  d.T  e.F
The image is found outside the centre of curvature, inverted, real and magnified. 
 

5. For an object situated outside the centre of curvature of a concave mirror, the image 
    has the following characteristics:

a. it is erect

b. it is virtual

c. it is real 

d. it is magnified

e. the image is found within the centre of curvature
 

Answer
a.F   b.F  c.T  d.F  e.T
For an object outside the centre of curvature of a concave mirror, the image
is inverted, real, minified ie. reduced in size and the image is found between the centre of curvature and the principal focus of the concave mirror.
 

6.  For an object situated within the principal focus of a concave mirror, the image 
      has the following characteristics:

a. it is erect

b. it is laterally inverted

c. it is real 

d. it is magnified

e. the image is found within the centre of curvature
 

Answer
a.T   b.T  c.F  d.T  e.F
The image is erect, laterally inverted, virtual, magnified and found within the concave mirror.

 

7.  For an object situated anywhere in front of a convex mirror, the image 
      has the following characteristics:

a. it is erect

b. it is laterally inverted

c. it is real 

d. it is magnified

e. the image is found within the centre of curvature
 

Answer
a.T   b.T  c.F  d.F  e.F
The image is virtual, erect and diminished. It is also laterally inverted and found within the mirror.

8. The following are true about total internal reflection:

a. it does not occur when light travel from a medium with lower refractive
    index to one with higher index.

b. it occurs when the incident ray exceeds the critical angle

c. it is used in binoculars

d. it explains why the anterior chamber angle can not be visualized with 
    a slit-lamp

e. a contact lens with a lower refractive index than the cornea may be used 
    to visualized the anterior chamber angle
 

Answera. T   b.T   c.T   d.T   e.F

Total internal reflection only occurs when the light travels from a medium

with a higher index to one with lower index. It occurs when the incident ray exceeds the critical angle. It is used in binocular and slit-lamps to invert images. To visualize the anterior chamber angle, a contact lens with a higher index than the cornea need to be used to over the total internal reflection.
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