experiment

1. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
Tabular Column
Result and
Conclusion
Thermal diffusivity of Brass
G NITHYA

2. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
Tabular Column
Result and
Conclusion
Outline
Theory
Exprimental Setup
Procedure
Tabular Column
Result and Conclusion

3. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
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Result and
Conclusion
Theory
The thermal diffusivity of a material is defined by the
ratio k/ ρ c where k is the thermal conductivity,ρ the
density and c the specific heat of a material.
If heat is generated at a point in the material, the speed
with which it diffuses out from the point is determined
by this ratio.
In steady state measurements of heat transport only the
conductivity plays a role. The diffusivity has no role to
play. When heat flow is not steady i.e the temperature
distribution takes place in the metal and it varies with
time.
When a sinusoidal wave is passed at one end of rod at a
frequency f then the temperature distribution along the
length of rod.

4. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
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Result and
Conclusion
Theory contd...
T(x,t)=To+exp(-αx)exp(φ ωt-βx)
Where To is the temperature of the surrounding
The amplitude decreases as heat waves move away from
the source. Also phase of the heat wave changes i.e it
increases linearly as one move away from source.
Also the diffusivity is given by-
D=ω/2αβ where ω is the frequency of the wave , is
the damping co-efficient and is the phase co-efficient.

5. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
Tabular Column
Result and
Conclusion
Experimental Setup

6. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
Tabular Column
Result and
Conclusion

7. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
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Result and
Conclusion
procedure
The heater is connected to a power supply.The current
through the heater coil will be approximately 0.5A.
The current through the coil and the voltage across the
coil gives the heat supplied. A switch in source is
toggled on for 5 minutes and off for 5 minutes regularly
. This interrupts the current periodically.
The thermocouple voltages are amplified by a DC
amplifier of amplification 100 and read on a milli-
voltmeter.For the first two cycles of heating no
thermocouple readings are taken.
We start counting the time from the instant the heater
is switched on after two cycles. Call this instant zero.
The reading is noted on differential amplifier. We will
find the amplitude and phase of thermocouple signals at
the period of heating by fourier analysis.

8. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
Tabular Column
Result and
Conclusion
Observation Table

9. Thermal diffusivity o
G NITHYA,
Theory
Exprimental Setup
Procedure
Tabular Column
Result and
Conclusion
Result and Conclusion
Therefore the thermal diffusivity of brass is 0.32 Cm2/s