Tag: simple electric circuits

Questions Related to simple electric circuits

LEDs are extensively used to replace . bulbs because:

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. it consumes less electricity

  2. have longer life

  3. has more power

  4. all of the above

Show answer
Correct Option: D
Explanation:

A light-emitting diode (LED) is a two-lead semiconductor light source. it is a p-n junction diode, which emits light when activated. LEDs have more power, more life time and consume less electricity than a bulb, thus these are extensively used to replace bulbs.

The glowing of electric bulb is based on _________ effect of current.

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. heating

  2. magnetic

  3. luminous

  4. none of the above

Show answer
Correct Option: A
Explanation:

Answer is A.
The electric bulb has a filament called tungsten when electricity passes through this filament, it heats up and glows. This heat is generated due to the passage of electric current and the drift of electrons due to the current and the resistance it causes.
Hence, The glowing of electric bulb is based on the heating effect of electric current.

When an electric bulb breaks, there is a mild bang due to:

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. The photo-chemical reaction between the enclosed gases.

  2. The compressed gases rushing out suddenly.

  3. The air rushing into fill the evacuated space.

  4. None of these

Show answer
Correct Option: C
Explanation:

Answer is C.

When an electric bulb breaks, there is a mild bang due to the sudden air rushing into fill the evacuated space.

In the bulb there is a -

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. Long wire

  2. Short wire

  3. Thin wire

  4. Wide wire

Show answer
Correct Option: C
Explanation:

as we know $Resistance =Resistivity\dfrac{Length}{Area}$

therefore, for making resistance more the radius of the wire should be less to make area less and make resistance more. as resistance is inversely proportional to area. therefore to make bulb we need thin wire. which is capable of withstanding high temperature and have high resistance.

An electric bulb converts electrical energy into

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. sound energy

  2. mechanical energy

  3. nuclear energy

  4. none of these

Show answer
Correct Option: D
Explanation:

Due to passage of electric current, the tungsten filament of the bulb gets heated up and glows. Thus an electric bulb converts electrical energy into heat energy as well as light energy.

Hence option D is correct.

The filament of an electric bulb is of tungston because

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. Its resistance is negligible.

  2. It is cheaper.

  3. Its melting point is high.

  4. filament is easily made.

Show answer
Correct Option: C
Explanation:

Tungston has very high melting point. Thus it does not melt even when a large amount of heat is produced in the bulb due to heating effect of current. Hence it is used as a filament in the bulb.

The filament of a bulb is usually a:

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. thin wire with many coils

  2. thick wire with many coils

  3. thin straight wire

  4. thick straight wire

Show answer
Correct Option: A
Explanation:

 When electric current goes through the filament, the filament glows. It may also be known as the electron emitting element in a vacuum tube. To make the bulb produce more light,the filament is usually made of coils of thin wire, also known as the coiled coil in order to get more emmision.

Generally, Filaments in incandescent light bulbs are made of tungsten as its melting point is very high.
Therefore, A is correct option.

The wire of an electric lamp has a:

physics simple electric circuits bulbs bulb bulb connected to an electric cell

  1. high resistance and a high melting-point

  2. high resistance and low melting-point

  3. low resistance and low melting-point

  4. low resistance

Show answer
Correct Option: A
Explanation:

Answer is A.

when choosing a material for a particular application, many different properties of materials must all be considered together (such as: melting point (MP), boiling point (BP), thermal conductivity, electrical resistivity, cost, etc.). For example, while Nichrome does have a much higher resistivity than Tungsten, Tungsten has a much higher melting point than Nichrome (Nichrome MP = 1400 C, Tung MP = 3422 C). For a typical incandescent light bulb, the Tungsten filament operates at approximately 2500 Celsius; notice that this is actually above the melting point of Nichrome!
Therefore, when you compare the melting points of the materials to the operating temperatures of a light bulb, you can quickly see why Tungsten is the preferred choice for filament wires. 
Pure tungsten has some amazing properties including the highest melting point (3695 K), lowest vapor pressure, and greatest tensile strength out of all the metals.Because of these properties it is the most commonly used material for light bulb filaments.
Hence, the wire of an electric lamp has a high resistance and high melting point.