1. What is refraction and why does it happen?
Refraction refers to the bending of light as it travels from one medium to another.
As light approaches the glass block from the left, it usually
splits in two - some of it reflects off the surface, and some of it
keeps going through
The light that goes through bends at the surface. The angle that
it bends at depends on what the two media are.
For example, light will bend a different amount when it goes
from air into glass than it does when it goes from air into water.
the law of reflection states that angle of incidence (i) = angle of reflection (r), and it is evident
that the incident ray and reflected ray have the same angle to the normal, which is a straight
line perpendicular to the surface of the glass block.
reflection happens why light bounces off an object too, and that enables us to see things!
During refraction, light bends towards the
normal
That means that the angle of refraction of
the refracted ray is smaller than the angle
of incidence.
Why does light enters the glass without being refracted?
Because the incident ray is perpendicular to the surface
Also, note that the emergent ray bends away from the normal.
Mirrors
A concave mirror has a surface that bulges inwards.
Images from a concave mirror are inverted and real (see video)
http://www.physicsclassroom.com/mmedia/optics/rdcmc.cfm
A real image refers to an image that come is produced from light that actually came from the
object.
On the other hand a virtual image forms in places where light cannot reach and therefore
cannot come from the object itself.
But when the object is really close, the image formed is upright, magnified and virtual

2. A concave mirror can also be used to focus sunlight for heating purposes in addition to the
ones listed in your textbook.
(Video: http://www.physicsclassroom.com/class/refln/u13l3a.cfm)
Convex mirror
A convex mirror is quite the opposite of a concave mirror, its surface bulges outwards.
A convex mirror causes light rays to diverge
whereas a concave mirror causes light rays to
converge.
The result is that are upright, distorted,
diminished and virtual.
What is an electric current?
A electric current refers to the rate of flow of electric charges through a conductor
motivated by a voltage and is measured in amperes
An electric current generates a magnetic field
But to MAKE USE of the magnetic field, you need to coil it

3. To make even better use by guiding the magnetic field lines, use a iron nail at the core of the
coils. This helps to form an electromagnet. Without the iron nail, there is very close field
lines. The closer the lines, the stronger the magnetic attraction.