Amount of radiant heat generated from a black and rough surface is greater
than the heat radiated from a white and polished surface, both the surfaces
being at the same temperature.
How????
Pls explain.
Answers
- Roughness in return, increases the actual surface area of the rough surface w.r.t. the smooth surface. & we know that, radiation is proportional to the surface area.
- As per heat chromatography, blacked area has the double radiating capacity than the white area..
- Indirectly, polished surface makes an invisible seperation from the surrounding, as the polished layer is better in reflection, but bad in radiation..
Hope this helps you
Answer:
Black colour absorbs more heat than white colour whereas white colour absorbs less heat than black colour. Hence, you must have seen that fuel carrying tankers are painted white as white colour radiates less heat. Similarly, people prefer wearing white clothes in summer as they absorb less heat and keep the body cool. People living at the hill tops paint the roofs of their houses black so as to absorb more heat and keep their houses warm.
By the following activity, you would know that white colour radiates less heat.
• Aim: To show that white colour radiates less heat.
• Materials: A black can, white can, water, thermometer.
• Procedure: Take the black can and the white can near a burning gas stove. Pour equal amounts of water in black can and white can. Insert the thermometer in the black and as well as white can and observe the reading.
• Observation: You would observe that the reading of the thermometer is more in the black can.
• Conclusion: Since the black can radiates more heat, the temperature reading was more in the black can. This proves that white colour radiates less heat.