How to Transfer of heat in a microwave oven

Heat Transfer TO Microwave Oven Short Mcq Questions Answers

Heat Transfer TO Microwave Oven:
Microwave radiation passes through the food in it Oven. Certain molecules in the food absorb energy from Microwave beam and start to move. It Movement produces heat cooks the food.

                                                      fig: Microwave Oven

The Largest Source of Heat Energy

Heat Energy Source, Solar Energy Short Question Answer

The Largest Source of Heat Energy:

Heat energy from the sun is known solar energy. Rays from the Sun heats the surface of the earth, the oceans and the air above.Taking a hint capacity of natural solar heating, scientists
Solar cells made ​​from which we can get electricity. When Sunlight touches the solar cells, it causes a chemical reaction and Electricity generated.  

Solar panels can heat water and cook food And solar cells can even run a car. Fossil fuels such as oil
Should be mined from the earth, and one day be used in them All up. But solar power is not over for millions of years.

                                                       fig: Solar Panel to Heat Air

Heat Energy-How is heat transferred from one thing to another

Heat Energy-How is heat transferred from one thing to another?

Ans:  heat is transferred by conduction, convection and radiation. Conduction means transfer of energy one molecule to molecule below. Whenever two materials approach each other heat flows samovar cooler material by conduction. Conversion is when the heat source heats a liquid or gas due to the movement of currents in a gas or liquid. This water is what water boils. Radiation is the transfer of heat in straight lines like a ray of sun. Direct radiation from the sun can be dangerous because it contains ultraviolet funds that harm our skin.

Electrical DC Machine Basic Formula Principle of Operation

Electrical DC Machine Basic Formula Principle of Operation

Some Basic Formula:

Right‐hand screw rule (cross product operation in vector algebra)

A1 X A2= A3

A1, A2, and A3 are vectors. Rotate RH fingers from the direction of the first vector , A1, to the

direction of the second vector, A2, through the small angle (<180o) between them; the direction

of A3 is then given by the extended RH thumb. In our applications, the magnetic field B is always

the second vector.

Given a straight conductor lying in a magnetic field, and oriented perpendicular to the direction

of the field. Let

B= magnetic flux density (also called magnetic induction), [T=tesla=weber/m2];

L=active length of conductor,[m]. u

Induced voltage (emf): 

E=B.L.u.sinα volts

u= speed of conductor perpendicular to its length[m/s];

α= small angle from u to B.

Direction of E : RH screw rule from u to B .

Developed force:

Fd= B.I.L newtons [N]

I= current through conductor, [A].

Direction of Fd : RH screw rule from I to B.

DC Circuit MCQ Short Questions Answers- Resistance in Series

DC Circuit MCQ Short Questions Answers- Resistance in Series

• When resistance is connected in series with the cell is halved, the current is not quite doubled, but is slightly less than why?

          This is due to the internal resistance r of the cell. Present transmitted by cell
          I = E / R+r ,
          When the external resistance R may R / 2, the current will be slightly less than 2I.