Hc-5 Absorption of Radiation by Black and White Surfaces
Published: Monday 13 March 2006 - Updated: Monday 28 March 2011
To demonstrate the relative absorption of black and white surfaces.
- Black and white thermoscopes
- Spotlight (Heat source)
- Beakers, red dye and stands
Click on pictures to enlarge.
Two thermoscopes have been constructed, one having a black surface, the other white. The pressure inside is reduced from atmospheric and equalized by the connecting tubes and valve A. The valve is then closed so that the two thermoscopes are independent. On turning on the 150 W spotlight a difference in fluid height indicates a difference in pressure between the two tubes due to different temperatures. This indicates that the black surface has absorbed more heat than the white surface.