Transcript Curved Mirrors

• There are some
mirrors that distort the
reflected image.
Cosmetic mirrors
magnify things, and
other mirrors make
things look smaller.
Curved Mirrors
Curved Mirrors
• A curved mirror is a
section of a sphere.
• If the outside surface
of the sphere is
reflecting, the mirror
is convex.
• If the inside surface is
reflecting, the mirror
is concave.
The characteristics (SALT) of the
image formed can be:
• larger, smaller or the same size of the
object
• inverted or upright
• in front or behind the mirror
• real or virtual
Parts of the concave mirror:
• Vertex (V) – the centre of the mirror
• Principal Axis (PA) — line that goes
through V
• Focus (F)—where the reflected rays of
parallel incident rays intersect
• Centre of Curvature (C)—the centre of the
sphere from which the mirror was cut
By drawing ray diagrams, you can
find out how the image would be.
•
Draw a ray parallel to the principal axis from
the top of object to the curved mirror. After
reflecting off mirror, the ray passes through the
focal point.
•
Draw a ray from the top of the object through
the focal point. The ray will be parallel to the
optical axis after reflecting.
• Draw a ray aimed at the vertex from the top of
object to the curved mirror. After reflecting off
mirror, the ray’s passes at the same angle below
the principal axis.
• Draw a ray aimed at the centre of curvature from
the top of object to the curved mirror. After
reflecting off mirror, the ray reflects back on
itself.
Use any two rules to determine the
characteristics of the image.
•
Draw the image as a vertical arrow with its tail
on the principle axis and the head at the point
where the two reflected rays meet.
The characteristics (SALT) of the
image formed are:
•
•
•
•
smaller
inverted
in front of the mirror
real
Useful Websites
http://thinkingoutofthebeaker.ca/DigitalSci/CurvedMirrors.html
http://www.edumedia-sciences.com/en/a308-concave-mirror
http://www.shermanlab.com/science/physics/optics/SphericalMirror.php
Practice your ray diagrams on the following. Draw
the image. State the characteristics of each image.
Answers
Convex Mirrors
Parts of the convex mirror:
• Vertex (V) – the centre of the mirror
• Principal Axis (PA) — line that goes
through V
• Focus (F)—where the reflected rays of
parallel incident rays intersect
• Centre of Curvature (C)—the centre of the
sphere from which the mirror was cut
By drawing ray diagrams, you can
find out how the image would be.
•
Draw ray parallel to principal axis. After
reflection, this ray travels as if it is coming from
the focus.
•
Draw line from top of object to centre, C. After
reflection, this ray travels back on itself as if it
is coming from the centre of curvature.
• Draw line from top of object to the focus, F. After
reflection, this ray travels back parallel to the
principal axis.
Use any two rules to determine the
characteristics of the image.
• The virtual image is drawn using a dotted line
with an arrow.
Tip: Images formed by a convex mirror are always
smaller, upright, and virtual.
Practice:
• Practice your ray
diagrams on the
following. Draw the
image. State the
characteristics of
each image.