Assignment

1. An aluminum plate of 0.05 m diameter and thickness 0.01 m is heated using coils by providing a supply of power 20 W. Fix the value of chamber temperature at -20°C. Compare the value of its emissivity with that of a black body at room temperature when the same power is applied. (σ = 5.67×10⁻⁸ W·m⁻²·K⁻⁴)
2. Calculate the value of emissivity of a brass plate whose radius is 0.03 m and thickness is 0.03 m at a chamber temperature of 50°C. A power supply of 33 W is applied to both the black plate and the test plate.
3. What happens to the value of emissivity when the initial power is increased from 33 W to 48 W for an iron plate? The diameter and thickness of the iron plate are given as 0.1 m and 0.05 m, respectively, with the chamber temperature at 20°C.
4. A copper plate of 0.04 m radius and thickness 0.06 m is heated with a supply of 65 W. The temperature of the chamber is 40°C. Calculate the emissivity of the plate.
5. How does the diameter of the metal plate affect the value of emissivity? If the diameter of a steel plate is increased from 0.05 m to 0.1 m, with 84 W power supplied, and the thickness of the plate is 0.08 m, with the chamber temperature at 80°C.