Tag: physics

Answer is A.

When we put any object in between the light source it forms a shadow of that object. The closer the object is to the source of the light, the more light it blocks out, so its shadow is bigger. But if the object is further away, it does not block out much light, and so the shadow is smaller.
Therefore, for the shadow of the ceiling fan to be formed on a wall opposite to the door, the electric bulb must be positioned on the wall having the door.

Option A $\rightarrow $ All light is electromagnetic wave. This option is correct as EM light does not need any medium to travel like EM wave.

Answer is A.

Most heating elements use Nichrome 80/20 (80% nickel, 20% chromium) wire, ribbon, or strip. Nichrome 80/20 is an ideal material, because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time. Material beneath this layer will not oxidize, preventing the wire from breaking or burning out.
Hence, nichrome is used as heating elements.

An electric iron is based on the principle of heating effect of current that heat is produced in the nichrome wire used in the iron due to the current flowing through it.

The overheating of electrical wiring in any circuit due to the flow of large current through it is called overloading of electric current.

Electrical working is based on Joule's law, i.e. heating effect of electric current in a conductor.

Electric Fan works on the principle of motor.

Nichrome is used for making heating element of electrical appliances. Because nichrome does not oxidize and burn easily at high temperature i.e.it has higher melting and boiling point than metals. Thus it does not melt even when a large amount of heat is produced due to passage of current. Moreover, It has higher resisistivity and consequently a higher resistance.Therefore, it will resist the flow of charges more, and lead to development of heat faster.

Tungsten is used in electric bulb because it has high melting point and it does not oxidize. Thus tungsten filament does not melt even when a large amount of heat is produced due to passage of current through the filament (via heating effect of current).

A device which works on Joule's law of heating ;