Questions and Answers - Recent questions and answers in Physics

Answered: Why is not advisable to wear dark colours in summer?

Wed, 21 Nov 2018 21:27:56 +0000

As the dark coloured clothes absorb heat wich produce heat so such clohes are not being worng during the summer.

Answered: How a green house becomes Heat Trap?

Wed, 21 Nov 2018 21:06:56 +0000

Light from the sun contains thermal radiations of long wave lengths as well as light an ultraviolt radiations of short wavelengths.Glass and transparent polythene sheets allow radiations of short wavelengths to pass through easily but no long wavelengths of thermal radiations.Thus, a greenhouse becomes a heat trap.

Answered: Why are sauce pans made of metals? Why are sauce pans made of metals?

Wed, 21 Nov 2018 21:04:57 +0000

Sauce pans are made of metal for quick heat transfer

Answered: What are the uses of convention current?

Wed, 21 Nov 2018 21:03:25 +0000

1. Convection currents set up by electric gas or cool heaters help to warm our houses and offices

2. Central heating system in buildings work on the priciple of convection.

3. Land breeze and sea breeze are the results of convection current.

Answered: Why a balloon inflated with hot air rises up?

Wed, 21 Nov 2018 21:02:42 +0000

Balloons inflated with hot air rise up.Air becomes lighter on heating.

Answered: What do you mean by bad conductors of heat?

Wed, 21 Nov 2018 21:01:00 +0000

Lighter or less materials like wood, air, etc. make poor conductors but good insulators because atoms are more spaced out or have more air it (such as foam). Atomic structure, the denser, usually the better. Metals. If it is an electric conductor, most probably it is a good heat conductor.

Answered: Describe the working of leslies cube?

Wed, 21 Nov 2018 20:58:27 +0000

Leslie's cube is a device used in the measurement or demonstration of the variations in thermal radiation emitted from different surfaces at the same temperature. ... The cube is made from a solid block of metal with a central cavity.

Answered: What measures are taken to conserve energy in houses?

Wed, 21 Nov 2018 20:57:04 +0000

1. Turn down the thermostat. Turning your thermostat down by just 1 degree can reduce your energy consumption by over 5%. You won't even notice the difference in room temperature. On the same note, don't heat rooms when you are not using them.

2. Decrease the hot water temperature:give your boiler reguler checkups,especially if you have had it for a few years. Wash economically

Answered: How many ways are to transfer of heat

Wed, 21 Nov 2018 20:55:42 +0000

There are three ways by which transfer of heat takes place .

1. Conduction 2. Convection 3. Radiation

Answered: Write down the names of four surfaces of Leslie Cube?

Wed, 21 Nov 2018 20:54:04 +0000

Four surfaces of Leslie cube are

1. A shining silvered surface

2. A dull black surface

3. A white surface

4. A colored surface

Answered: Why does a cup of hot tea become cold after sometime?

Wed, 21 Nov 2018 20:52:45 +0000

It is all about the thermal properties of water and simple physics; heat moves away from the area of higher concentration to the area of lower concentration.

Answered: Why do we kept plants under the roof of fiber glass or plastic sheet in winter?

Wed, 21 Nov 2018 20:50:57 +0000

Glass and transparent polythene sheets do not allow them to escape out easily and are reflected back in the green house.This maintains the inside temperature of the green house.Green house effect promises better growth of some plants.

Answered: Define radiation?

Wed, 21 Nov 2018 20:49:54 +0000

Radiation is the mod of transfer of heat from one place to another in the form of waves called electromagnetic waves.

Answered: What are thermals?

Wed, 21 Nov 2018 20:47:49 +0000

Glider poilts use upward movement of hot air currents due to convection of heat.These rising currents of hot air are called thermals.

Define rate of flow of heat?

Wed, 21 Nov 2018 20:46:54 +0000

Define rate of flow of heat?

Answered: What is meant by convection currents?

Wed, 21 Nov 2018 20:45:36 +0000

Heat energy can transfer by convection when there is a significant difference in temperature between two parts of a fluid. When this temperature difference exists, hot fluids rise and cold fluids sink, and then currents, or movements, are created in the fluid.

Answered: How do thermals help birds to fly for hours without flapping their wings?

Wed, 21 Nov 2018 20:43:40 +0000

The birds stretch out their wings and circle in these thermals .The upward movement of air helps birds to climb up with it. Eagle's hawks and vultures are experts thermal climbers.After getting a free lift birds are able to fly for hours with out flapping their wings.

Answered: What is the thermos flask؟

Wed, 21 Nov 2018 20:42:00 +0000

The thermos flak consist of a double walled glass vessel. It reduces the transfer of heat by conduction, convection and radiation.

Answered: What is the scientific reason to wear white and light coloured cloths in summer?

Wed, 21 Nov 2018 20:37:52 +0000

We wear white and light colured cclothes in summer which reflect most of the heat radiation reaching us during the hot day.

Answered: How does heat reaches us from the sun?

Wed, 21 Nov 2018 20:36:30 +0000

Since, there is vacuum in large region between sun and earth so heat is transferred to the earth by method of raditation only.

Define thermal conductivity on what factors the rate of flow of heat depends?

Wed, 21 Nov 2018 20:35:11 +0000

Define thermal conductivity on what factors the rate of flow of heat depends?

Explain the application and consequences of radiation?

Wed, 21 Nov 2018 20:34:02 +0000

Explain the application and consequences of radiation?

Answered: Define conductors and non conductors explain their uses?

Wed, 21 Nov 2018 20:32:36 +0000

An electrical conductor is a substance in which electrical charge carriers, usually electrons, move easily from atom to atom with the application of voltage. ... Gases are normally poor conductors because the atoms are too far apart to allow a free exchange of electrons.

Answered: Define thermals. How it help the birds to fly for hours without flapping their wings?

Wed, 21 Nov 2018 20:28:04 +0000

The birds stretch out their wings and circle in these thermals. The upward movement of air helps birds to climb up with it. Eagles, hawks and vultures are expert thermal climbers. After getting a free lift, birds are able to fly for hours without flapping their wings.

What do you know about global warming and green house effect explain?

Wed, 21 Nov 2018 20:26:50 +0000

What do you know about global warming and green house effect explain?

Answered: What are the consequence and applications of convection?Explain

Wed, 21 Nov 2018 20:25:33 +0000

Explain convection of air by heat radiators. Most of the heat from a radiator is circulated by convection. Warm air around the radiator rises above the radiator and cooler air replaces it. The cooler air gets heated by the radiator and it rises and cooler air moves in to replace it.

How heat can be transfer through convection? explain with the help of experiment.

Wed, 21 Nov 2018 20:24:07 +0000

How heat can be transfer through convection? explain with the help of experiment.

Answered: What do you know about sea breeze and land breeze explain?

Wed, 21 Nov 2018 20:22:25 +0000

The wind will blow from the higher pressure over the water to lower pressure over the land causing thesea breeze. The sea breeze strength will vary depending on the temperature difference between theland and the ocean. At night, the roles reverse. The air over the ocean is now warmer than the air over the land.

Define radiation explain with an experimentریڈی

Wed, 21 Nov 2018 20:21:08 +0000

Define radiation explain with an experimentریڈی

Answered: What are some uses of conductors and non-conductors.

Wed, 21 Nov 2018 20:19:04 +0000

Conductors conduct electrical current very easily because of their free electrons. Insulators oppose electrical current and make poor conductors. Some common conductors are copper, aluminum, gold, and silver. Some common insulators are glass, air, plastic, rubber, and wood.

Answered: Why we feel coldness on sitting under the fan after taking a bath?

Wed, 21 Nov 2018 20:13:30 +0000

The air moving across the moisture causes it to evaporate.۔ Evaporation being a cooling process, it makes you feel cold.

Answered: What is thermometry ?

Wed, 21 Nov 2018 20:10:27 +0000

The branch of physics which deals withthe measurement of tempeature is called thermometry.

Answered: What happens when two bodies at different temperature are brought in thermal contact?

Wed, 21 Nov 2018 20:08:28 +0000

Heat is the energy that is transferred fom one body to the other in thermal contact with each other as a resultof the difference of temperature between them,

Answered: How is cooling produced by evaporation explain?

Wed, 21 Nov 2018 20:05:13 +0000

During evaporation fast moving molecules escape out from the surface of the liquid .Molecules that have lower kinetic energies are left behind..This lowers the average kinetic energy of the liquid molecules and the temperature of the liquid.So cooling produces in the evaporation.

Answered: What is meant by evaporation?

Wed, 21 Nov 2018 20:03:03 +0000

Evaporation is the changing of a liquid into vapours from the surface of the liquid with out heating it. Evaporaion is escaping out of fast moving water molecules from the surface of a liquid with out heating .

Answered: What is thermometric property ?

Wed, 21 Nov 2018 20:01:20 +0000

change of resistance Expansions Change of color Change of physical state

Answered: Why wet clothes dry up quickly in summer than in winter?

Wed, 21 Nov 2018 19:51:50 +0000

Simple.because in summer the temperature is high so the air can absorb more moisture.in winters humidity(moisture in air)is lowand temperature is low so evaporation is slower.

Answered: How does boiling differ from evaporation?

Wed, 21 Nov 2018 19:50:00 +0000

Evaporation is a slow process from the liquid to gasesous state which takes place at the surface of a liquid and at all temperture.On the other hand ,boiling process is a rapid change of a substance from the liquid to the gaseous stste which place throughout the mass of the liquid at a definite temperature.

Answered: Name the property used in strip thermometer?

Wed, 21 Nov 2018 19:47:05 +0000

Bimetal strips are used for various purposes..Bimetal therometers are used to measure temperatures especially in furnaces and ovens.

Answered: Enlist some application of thermal expansion?

Wed, 21 Nov 2018 19:44:59 +0000

Some of applications of thermal expansion are given below:

i.In thermometers thermal expansion is used in temperature measurements.tO OPEN the cup of a bottle that is tight enough ,immerse it in hot water for some minutes.Metal cap expands and become loose .it would now be easy to turn it to open

Answered: What is meant by latent heat of vaporization?

Wed, 21 Nov 2018 19:41:31 +0000

The amount of heat required to change 1 kg substance from liquid to vapour state without change of temperature is called latent heat of vaporization.

Answered: What is meant by absolute zero?

Wed, 21 Nov 2018 19:32:59 +0000

The zero on Kelvin scale is called absolute zero and is equal to -273 degree C.

Answered: Why water is used in cooling system ofvehicles?

Wed, 21 Nov 2018 19:29:36 +0000

The cooling system of vehicles uses water tocary away unwanted thermal energy.In vehicles, large amiunt oh heat is produced by its engine due to which its temperature goes on increasings the engine would cease unless it is not cooled down.

Answered: What is meant by internal energy of a body?

Wed, 21 Nov 2018 19:27:52 +0000

In thermodynamics, the internal energy of a thermodynamic system, or a body with well-defined boundaries, denoted by U, or sometimes E, is the total of the kineticenergy due to the motion of molecules (translational, rotational, vibrational) and the potential energy associated with the vibrational and electric energy

Answered: Why is the latent heat of vaporization much larger than the latent heat of fusion?

Wed, 21 Nov 2018 19:26:06 +0000

The energy required to completely separate the molecules, moving from liquid to gas, is much greater that if you were just to reduce their separation, solid to liquid. Hence the reason why the latent heat of vaporization is greater that the latent heat of fusion.

Answered: How different scales of temperature can be differentiate from each other?

Wed, 21 Nov 2018 19:24:39 +0000

Temperature Scales. There are three temperature scales in use today, Fahrenheit, Celsius and Kelvin. Fahrenheit temperature scale is a scale based on 32 for the freezing point of water and 212 forthe boiling point of water, the interval between the two being divided into 180 parts.

Answered: Explain briefly specific heat of solids and liquids. and in which unit it is measured?

Wed, 21 Nov 2018 19:23:00 +0000

One older unit of heat is the kilogram-calorie (Cal), originally defined as the energy required to raise the temperature of one kilogram of water by one degree Celsius, typically from 14.5 to 15.5 °C. The specific average heat capacity of water on this scale would therefore be exactly 1 Cal/(C°⋅kg).

Answered: Define linear thermal expansion in solid?

Wed, 21 Nov 2018 19:21:34 +0000

Thermal expansion is the tendency of matter to change in volume response a coefficient linear thermal (cte,, or 1) material property that indicative extent which mate rial expands upon if does not go through phase change, can be easily related temperature. Have an areal thermal expansion.

Answered: Define volume thermal expansion solid?

Wed, 21 Nov 2018 19:17:02 +0000

Thermal expansion is the tendency of matter to change in shape, area, and volume in response to a change in temperature. ... The relative expansion(also called strain) divided by the change in temperature is called the material's coefficient ofthermal expansion and generally varies with temperature.

Answered: What is thermometer? state some properties of thermometric liquid.

Wed, 21 Nov 2018 19:15:16 +0000

Thermometric properties commonly used for thermometers include: Volume: Most objects expand when they are heated.The volume of mercury or alcohol expands when the temperature increases. Both are often used in thermometers. Electrical resistance:The resistance of a copper wire increases with temperature.