If a burning log is a black object with a surface area of 0.35 m2 and a temperature of 800 ˚C, how much power does it emit as thermal radiation?
To calculate the power emitted by the burning log as thermal radiation, we can use the Stefan-Boltzmann Law, which states that the power radiated by an object is proportional to the fourth power of its temperature and its surface area.
The formula is:
P = σ * A * ε * T^4
Where:
P is the power emitted as thermal radiation,
σ is the Stefan-Boltzmann constant (approximately 5.67 x 10^-8 W/m^2*K^4),
A is the surface area of the object,
ε is the emissivity, and
T is the temperature in Kelvin.
Now, let's compute the power emitted by the burning log using the given values.
1. Convert the temperature from Celsius to Kelvin:
T(K) = T(°C) + 273.15
T(K) = 800 + 273.15
T(K) ≈ 1073.15 K
2. Plug the values into the formula:
P = σ * A * ε * T^4
P = 5.67 x 10^-8 * 0.35 * 1 * (1073.15)^4
3. Calculate the power:
P ≈ 1981.25 W
Therefore, the burning log emits approximately 1981.25 watts of power as thermal radiation.