BIPRISM

Here we determine the wavelength of a monochromatic light by forming interference fringes.

EDSER-BUTLER FRINGES

Here we determine the thickness of air film enclosed between two semi silvered glass plates.

SEARLE'S VIBRATION MAGNETOMETER

Here we compare the magnetic moments of two bar magnets.

DEFLECTION MAGNETOMETER

Here we determine the pole strength and hence the moment of a bar magnet, keeping it vertically on the arms of a deflection magnetometer.

POTENTIOMETER- e.m.f of a Thermocouple

Here we measure the e.m.f of a thermocouple at different temperatures using a potentiometer, assuming the e.m.f of an accumulator.

CAREY FOSTER'S BRIDGE

Here we determine the temperature coefficient of resistance of the given coil wire.

MIRROR GALVANOMETER

Here we determine the figure of merit for current of the moving coil galvanometer. The principle utilised is that the current sensitivity of a mirror galvanometer is the current required to produce a deflection of one millimeter on a scale placed at a distance of one meter from the mirror.

DETERMINATION OF PLANCK'S CONSTANT USING LIGHT EMITTING DIODES

AIM OF THE EXPERIMENT: To determine the value of Planck’s constant ‘h’ by using light emitting diode.
APPARATUS:Regulated DC power supply, Light emitting diodes, Digital voltmeter and Digital microammeter.
PRINCIPLE: Planck’s constant ‘h’ is given by,
h = eVl/c = eV/n where ‘e’ is the electron charge, ‘V’ the turn on voltage corresponding to a LED which emits light of wavelength ‘l’, frequency ‘n’and ‘c’ the velocity of light. If we draw a graph between turn on voltage ‘V’ and frequency ‘n’, from the slope of the graph, we can determine the Planck’s constant
PROCEDURE: Connections are made as shown in figure. Turn on voltages of different light emitting diodes are taken and plotted against corresponding frequencies. Slope of the graph will give Planck’s constant.

RESULT:
Planck’s constant =