Procedure for performing real lab:
- Remove the disc from the bottom of the hemisphere and switch on the heater and allow the water to flow through it.
- Allow the hemisphere to reach the steady state and note down the temperature T1, T2, T3 .
- Fit the disc (black body) at the bottom of the hemisphere and note down its rise in temperature with respect to time till steady state is reached.
- A graph is plotted with temperature of disc along Y-axis and time along X-axis as shown.
- Find out the slope dT/dt from the graph.
Procedure for performing simulator:
- Choose desirable values of water temperature, surrounding temperature, mass and radius of the disc using the sliders.
- Click the "Power ON" button and wait till T1, T2 ,T3 reach steady state. Note down its values.
- Putting T4 button, click "Fit the disc'' option.
- Note down T4 at different intervals of time till it reaches steady state.
- Plot Temperature-Time graph and determine its slope .
- Determine Stefan's constant '' using the given formula.
Observations:
Calculations:
Mass of the copper disc = ...... kg
Specific heat of copper = ...... Jkg-1
Radius of the disc = ..... m
Area of the disc = ......m2
Slope of the graph = ……Ks-1
Substituting the values in the given expression,
= …………………………… Wm-2K-4
Result:
Stefan-Boltzmann’s constant σ =……………. Wm-2K-4