CBSE Class 11-science Physics Transfer Of Heat By Radiation
- There are two thin spheres A and B of the same material and same thickness.They emit like black bodies.Radius of A is double that of B.A and B have same tempt. T .When A and B are kept in a room of tempt T0(less than T),the ratio of their rates of cooling (rate of fall of tempt) is
- Two bodies A and B have emissivities 0.5 and 0.8 respec .At some tempt the two bodies have emissive powers at these tempt.
- Explain the working of room heater. How can we increase the efficiency of convections in radiator of a room heater?
- By what mode of heat transfer is mercury heated?
- Which of the three modes of transfer of heat is the fastest?
- One thermometer is placed half metre above the tip of the fire and one thermometer is placed half metre at the side of the fire. Would the readings of the two thermometers be same or different and why?
- If a liquid is heated from top, then by which mode the transfer of heat would take place?
- Why is a new quilt warmer than an old quilt?
- What are thermal radiations? Give some of its basic characteristics.
- A wooden plank of 0.025 m is attached to an insulation of 0.075 m. The temperature inside it is 25 ˚C and the outside temperature is 4 ˚C. T is the interface temperature. Take: K(wood)= 0.80 J/s m ˚C, K(insulation)= 0.20 J/s m ˚C. Calculate how much heat energy flows through the wall per second?
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