Perfect Black Bodies And Radiation (physics Only) (GCSE Physics)

If a body has emissivity e and temperature T, the total emitted power per unit area = esT4. If T doubles and e stays same, emitted power changes by factor

Kirchhoff’s law of thermal radiation (simple form) states: at thermal equilibrium, the emissivity of a body equals its absorptivity at each wavelength. This implies that

Which statement about emission and absorption for a perfect black body is correct?

A black body in a furnace at uniform temperature emits radiation. Which is true about directionality of emission?

A grey body has emissivity less than 1 but independent of wavelength. Compared with a perfect black body at the same temperature, a grey body

A material’s emissivity determines how well it radiates energy. If emissivity is 0.6, then at a given temperature the emitted power per unit area is

Which real object is closest in behaviour to a perfect black body in the infrared region?

If a black body’s absolute temperature is 290 K, the peak of its emitted spectrum is about 10 micrometres (µm). If its temperature were raised to 580 K (double), the peak would be about

Which statement about selective emitters is correct?

The Stefan–Boltzmann concept (qualitative) states that for black bodies, the total radiated power per unit area is proportional to the fourth power of absolute temperature. Which consequence follows?

The spectral peak wavelength of a perfect black body shifts when its temperature changes. If the temperature increases, the peak wavelength