Fermi energy calculation-an easy method.

Fermi energy of a metal is the energy associated with an electron when it is in Fermi level. Fermi level is the top most filled energy level by an electron in a metal substance. A simple method of calculation of Fermi energy is by employing a heating experiment. Take the metal whose Fermi energy is to be calculated in the fine coil form. Note the length of the coil and immerse it in water in a container. Two ends of the coil is connected to waterproof connectors. An ammeter is connected in series to measure the current flowing through the coil and a voltmeter is connected across the coil to measure voltage developed across the coil. Note the current and voltage for different temperatures. In each case by applying Ohm's law, you can calculate the resistance of the coil. Now draw temprature-resistance graph in a graph sheet and find out the slope of the curve. Fermi energy can now be calculated by using the relation,

Fermi energy EF=3TTrrrrxslopexslope/LL where "L' is the length of the wire, 'r' the radius of the wire and T the lab temperature.

Acoustic grating method of ultrasonic study

Here ultrasonic waves are produced by inverse piezoelectric effect by using a quartz crystal. This ultrasonic waves are allowed to travel through a water column and then is allowed to reflect back by a mirror. This forms a grating because in the liquid column a stationary wave pattern is formed with nodes and antinodes. Nodal points blocks light or they are opaque to light. Antinodal points transmit the light. If you carry out diffraction study using a spectrometer and a source of monochromatic light, u can observe diffraction pattern. You find out the angle of diffraction, substitute it in grating equation to find out wavelength of ultrasonic waves. From wavelength, we can easily find out velocity if frequency is known.

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 =