Vernier Calliper

Meter ruler gives measurements with the accuracy of 1 mm. when the accuracy of 1 mm is not sufficient for a measurement; venire caliper is used instead of meter ruler.In order to take a reading,calculate the least count at first.Record the number which correspond to the last line on the main scale which falls before the zero of the vernire scale.Count to the right on the vernire scale until you reach a vernire line which coincide with a line on the main scale and record the number of that vernire line. (Vernire coincidence number) and multiply it with the least count.

Ripple Tank

The ripple tank is usually illuminated from above, so that the light shines through the water. Some small ripple tanks fit onto the top of an overhead projector, i.e. they are illuminated from below. The ripples on the water show up as shadows on the screen underneath the tank. All the basic properties of waves, including reflection, refraction, interference and diffraction, can be demonstrated.Ripples may be generated by a piece of wood that is suspended above the tank on elastic bands so that it is just touching the surface. Screwed to wood is a motor that has an off center weight attached to the axle. As the axle rotates the motor wobbles, shaking the wood and generating ripples.

Total Internal Reflection

Total internal reflection is a phenomenon that happens when a propagating wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is greater than the critical angle, the wave cannot pass through and is entirely reflected. The critical angle is the angle of incidence above which the total internal reflectance occurs. This is particularly common as an optical phenomenon, where light waves are involved, but it occurs with many types of waves, such as electromagnetic waves in general or sound waves.