Boltzman Constant Kit
Conventional method to determine Boltzman Constant (k) make use of the block body Radiation and its two famous laws i.e. Wien’s displacement law and Stefan’s law . These methods are time consuming and very often lead to comparatively less accurate results.
The V – I characteristics of a semiconductor diode can be used to determine Boltzman Constant accurately and with simple equipment that can be handled with ease and convenience .
Principle : The diode equation is given by:
where V = voltage across the diode
I = forward current at voltage V
Io = reverse saturation current
k = Boltzmann Constant
T = Temperature in Kelvin
n = a constant , characteristic of the material from which the diode is
made , for Ge diode, n = 1 while n = 2 for Si diode.
If V >> kT/e , the Boltzmann constant can be expressed as
where is the slope of the straight line drawn between V and ln(I)
INSTRUMENT
The experimental kit provides the following facilities :
(a) A digital millivoltmeter (0 – 9.99 V) to measure the voltage across the diode.
(b) A highly stabilized power supply whose voltage can be varied in steps of 1 mV using a ten – turn potentiometer.
(c) A digital current ammeter ( 0 – 500 mA).
(d) Diodes: Silicon diodes & Germanium diodes.
