Physics Questions

Silver is the best conductor of both heat and electricity among metals with a thermal conduction value of about 430 W/(mK).

Gold and copper both come respectably close to silver.

Copper being significantly less costly it is often chosen over silver in many applications.

Heat energy can be transferred by three major methods. They are 

1. Conduction,

2. Convection and

3. Radiation.

Conduction is the movement of heat through a substance by the collision of molecules

Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy.

Radiation is the transfer of energy by means of photons in electromagnetic waves governed by the same laws. It occurs through a vacuum or any transparent medium.

There are two types of printers we use. They are 

* Laser Printers and

* Inkjet Printers.

And again Laser printers are of two categories. They are ::

1. Personal laser printers  and

2. Office laser printers.

From the given circuit,

The resistors R1 and R2 are in parallel connection and R3 is in series with R1 & R2

The equivalent resistance of R1 and R2 is

Req = (12 × 4)/(12 + 4) = 3 Ω.

Adding R3 in series with the pair gives

R = Req + 9

R = 3 + 9

R = 12 Ω.

Magnetism in materials is due to circular motion of electrons.