·Observations Schematic diagram The Electrical energy dissipated in the transistor is transferred to the surface by conduction and then added to the surrounding air by convection. Heat is also removed from the surface by radiation. -For heat to transfer from the surface to the surrounding air, surface temperature must be higher than ambient temperature The higher the dissipated power,the higher its surface temperature.• Observations – Schematic diagram – The Electrical energy dissipated in the transistor is transferred to the surface by conduction and then added to the surrounding air by convection. – Heat is also removed from the surface by radiation. – For heat to transfer from the surface to the surrounding air, surface temperature must be higher than ambient temperature – The higher the dissipated power, the higher its surface temperature