PRELIMINARY QUESTIONS
1. When looking obliquely at a window, you may see two reflected
images close to each other. What causes this?
The two reflected images close to each other are caused by the
double reflection on the window. There will be reflection from
both the inner and outer surface of the glass.
2. Binoculars and periscopes use prisms instead of mirrors to
reflect light. How does this happen? Draw a sketch.
Binoculars and periscopes use prism instead of mirrors to reflect
light because they have a higher total internal reflection.
3. When hot air rises above a stove top, objects behind it
appear to shimmer. What causes this?
When hot air rises above a stove top, objects behind it appear to
shimmer because the density of air changes. This causes the
refraction and fluctuating images of the background.
4. In Fig.1, which refractive index is greater, na or nb? How
would the figure appear if it was the other way round?
Draw a sketch.
In Fig.1, the refractive index which is greatest is nb.
, ANALYSIS
1. What is the relationship between the angles of
incidence and reflection?
The angle of incidence and reflection is that the angle of
reflection is the same as the incidence.
2. What is the relationship between the object and image
distances for a plane mirror?
The distance between the object and image distances are equal
for a plane mirror.
3. Plot a graph of sin𝜃a (y axis) vs. sin𝜃b (x axis) and, from the
slope, calculate the refractive index of the rectangular block.
(The refractive index of air is 1.00029 which you can
approximate to 1.0.)
4. Calculate the refractive index of the semicircular block.
5. What happened to the refracted ray when the angle of
incidence was larger than the critical angle?
1. When looking obliquely at a window, you may see two reflected
images close to each other. What causes this?
The two reflected images close to each other are caused by the
double reflection on the window. There will be reflection from
both the inner and outer surface of the glass.
2. Binoculars and periscopes use prisms instead of mirrors to
reflect light. How does this happen? Draw a sketch.
Binoculars and periscopes use prism instead of mirrors to reflect
light because they have a higher total internal reflection.
3. When hot air rises above a stove top, objects behind it
appear to shimmer. What causes this?
When hot air rises above a stove top, objects behind it appear to
shimmer because the density of air changes. This causes the
refraction and fluctuating images of the background.
4. In Fig.1, which refractive index is greater, na or nb? How
would the figure appear if it was the other way round?
Draw a sketch.
In Fig.1, the refractive index which is greatest is nb.
, ANALYSIS
1. What is the relationship between the angles of
incidence and reflection?
The angle of incidence and reflection is that the angle of
reflection is the same as the incidence.
2. What is the relationship between the object and image
distances for a plane mirror?
The distance between the object and image distances are equal
for a plane mirror.
3. Plot a graph of sin𝜃a (y axis) vs. sin𝜃b (x axis) and, from the
slope, calculate the refractive index of the rectangular block.
(The refractive index of air is 1.00029 which you can
approximate to 1.0.)
4. Calculate the refractive index of the semicircular block.
5. What happened to the refracted ray when the angle of
incidence was larger than the critical angle?
