The PH0418A Crook's Radiometer demonstrates heat transfer.
This radiometer comprises a partly evacuated glass bulb about 70mm in Diameter mounted on a round base, containing at its centre a fine pivot which supports four light weight metal arms. One side of each vane is blackened , the reverse side is bright. When the light strikes the wings, it transfers the heat to each one, but not at the same degree. The light wings reflect the rays and the dark wings absorb the rays. As the light gets brighter it creates more heat and spins the wings faster.