PHYSICS [2 Mark Question Answer]

The heat generated by the engine is efficiently radiated due to the dull black paint. The black paint emits the most heat through radiation (highest emissivity). This improves the heat transfer out of the radiator when air isn’t moving through the radiator.

Blackbody radiation, energy radiated by any object or system that absorbs all incident radiation. The term usually refers to the spectrum of light emitted by any heated object; common examples include the heating element of a toaster and the filament of a light bulb.

The process by which impure and warm air inside a room is continuously replaced by fresh air from outside is called ventilation. The carbon dioxide rich exhaled air , being warm and lighter rises up It then passes out through the ventilators in a room This causes a drop in pressure within the room Thus the cold can fresh air enters from the doors and windows to fill up the gap This continuous circulation of air is maintained with the room by convection currents.

Convection is not possible in solids because for convection to take place the molecules of a substance should be free to move like liquids and gases. The molecules of a solid are tightly packed together, thus making it difficult for molecules to move around for convection to take place.

Convection is the process of transmission of heat by the actual movement of particles between different temperatures. The particles absorb heat energy from the hot source and it will move into the colder region. The thermal process responsible for the formation of weather is convection in the air.

The iceboxes are generally double-walled iron boxes. The space in between the wall is filled with glass wool, which is a bad conductor of heat. So, the heat from outside does not reach the ice and hence it does not melt.

A chair made of iron appears colder because iron being a good conductor of heat, it looses its heat to the surrounding at night. But the wooden chair remains the same because wood is a bad conductor of heat and so no heat is lost from it.

Metals are used for the manufacturing of cooking vessels because they can absorb heat energy and transfer it into food efficiently. Mercury is used as a thermometric liquid because it is a good conductor of heat. Copper tubing is used in automobile radiators to cool the hot water coming from the side of engine.

The process of transfer of heat energy without the actual flow of matter is known as conduction. Or wan say conduction is the process of transfer of transmission of heat energy in solids without the actual movement of particles from their position. Conduction is happening in solids because, in solids, particles are having very small interparticle space and they are not free to move. In liquids and gases, the interparticle spaces are large as compared to that of solids, and particles are free to move, hence convection is possible in liquids and gases.

Conduction is the process of transfer of transmission of heat energy in solids without the actual movement of particles from their position. If you are holding a copper rod in the flame of a spirit lamp, after some time you can feel hotness in your hand since thermal energy from flame is getting conducted through the copper rod. The state of matter in which conduction takes place is solid. Mercury is the only liquid in which conduction takes place.