A Leslie cube is a thin-walled cube that can be filled with boiling water in order to…
PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
A Leslie cube is a thin-walled cube that can be filled with boiling water in order to demonstrate to physics students how differently coloured surfaces radiate energy at different rates. A typical Leslie cube has faces each of an area 100 cm2 and holds 1 kg of water.
(a) Calculate the time required for a heater rated at 1000 W to raise the temperature of 1 kg of water from 20∘C to its boiling temperature of 100∘C . (The specific heat capacity of water is 4.2 kJkg−1∘C−1 .)
(b) Outline any assumptions you may have made in answering part a.
(c) Making the assumption that an insignificantly small amount of energy is required to heat up the walls of the cube to the same temperature as the boiling water, calculate the rate at which energy is being radiated from the matte black face ( ϵ=1.0 ) of the cube.