A series of experimental data for several ideal black bodies are plotted on a log–log graph with total emissive power E (W m−2) on the vertical axis and absolute temperature T (K) on the horizontal axis.
(i) Using the relationship between E and T, show that the graph must be a straight line and determine its slope.
(ii) What physical constant is represented (apart from numerical factors) by the intercept of this line on the vertical axis? Explain your answer briefly.
(iii) If the temperature of a black body increases by 3\%, estimate, without direct calculation of E, the approximate percentage increase in its emissive power.