3B SCIENTIFIC PHYSICS 1008523 Manual de instruções - Página 2

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2. Description

The Stefan-Boltzmann lamp is a high tempera-

ture source with a tungsten filament. It is de-

signed to produce thermal radiation and for in-

vestigating how such radiation depends on the

temperature. It can be used to confirm the

Stefan-Boltzmann law, as stated in the following

equation:





 



P in this equation is the power radiated, T is the

absolute temperature of the filament, A is the

area of the filament's surface, σ is the Stefan-

Boltzmann constant and ε is a dimensionless

constant of a value between 0 and 1. The tem-

perature of the lamp can be determined from

the resistance of the filament.

The filament represents a good approximation

of a point source of heat radiation and is thus

highly suitable for investigating the inverse

square law for heat radiation.

3. Equipment

1 Stefan Boltzmann Lamp

1 Stand Rod, 130 mm long

4. Technical data

Nominal voltage:

Nominal current:

Nominal power:

Max. operating parameters:

Maximum temperature

of filament:

Distance of filament

from rod:

5. Sample measurements

Additionally required:

1 Thermopile

1 DC Power Supply, 20 V, 5 A (@230V)

1 DC Power Supply, 20 V, 5 A (@115V)

1 Digital Multimeter P3340

2 Digital Multimeters P1035

2 Barrel Feet, 1 kg

1 Set of 15 Safety Experiment Leads, 75 cm

12 V DC

1.75 A

21 W

13 V DC/2 A

3600 K

25 mm

1000824

1003312

1003311

1002785

1002781

1002834

1002843

5.1 Measurement of filament resistance at

room temperature



Insert one of the measuring leads into the

COM socket of the digital multimeter P3340

(1002785) and one into its V

then short the leads together.





Select the

measuring range, wait for

zero to be displayed and then briefly press

the REL button.



Break the contact between the leads and in-

sert them into the sockets of the Stefan-

Boltzmann lamp.



Read off the resistance value R

a note of it (Tab. 1).



Remove the measuring leads.



Use the multimeter's temperature sensor to

measure the ambient temperature T

vicinity of the lamp in Kelvin and make a

note of it (Tab. 1).

Tab. 1: Value of filament resistance measured at

room temperature

ref



mA socket,

and make

ref

in the

ref

0.541 

297 K