Measurement of Planck’s constant through Black Body Radiation
Experimental Setup
Procedure
The experimental setup is shown in Figure (5). Complete the assembly as sketched in figure (5a). Connect a 60W incandescent light bulb to the variac through an ammeter (digital mulimetrer) in series. A digital voltmeter is also connected in parallel to measure voltage values. The variac is an AC transformer that gives variable voltages.
Note: Make sure the variac is unplugged when you are making electrical connections. Wear safety gloves. Remember, never touch bare electric wires.
You are provided with a cylindrical tube with bulb fitted inside it. Inert this cylindrical tube into the black box. Fix the bulb position as shown in Figure (5c). Now assemble the optical components in a way shown in Figure (5d) and connect the silicon photodiode to digital oscilloscope.
Observation Table
| V (V) | ΔV (V) | I (mA) | ΔI (mA) | R (Ω) | ΔR (Ω) | P (W) | ΔP (W) | T (K) | ΔT (K) | Irad (mV) | ΔIrad (1%) (mV) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 34 | 0.4 | 100 | 1 | 329 | 6 | 3.31 | 0.09 | 976 | 12 | 0.4 | 1% of I value |
| 57 | |||||||||||
| 210 |
Table 2: Model table for experimental results.