Tag: bulb connected to an electric cell

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

The filament of an electric bulb is of tungsten because

  1. its resistance is negligible.

  2. it is cheaper.

  3. its melting point is high.

  4. filament is easily made.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Incandescent light bulbs use heat generated by the resistance of the filament to create light. to get white light you need the filament to reach 2700-3300 K to give off white yellow light.

The reason tungsten is used is because it has the highest melting temperature of any element at 3600 K.

To generate a lot of heat you need a big resistance. Resistance(R) is dependent on resistivity ($\rho$) but also on the length (l) of the wire and the width (w).

R $=\dfrac{\rho \times l}{A} $

Having a big resistivity helps to create a big resistance but since you can change the thickness and length of the filament in light bulb (the filament is looped to increase the length) you can control the resistance. 

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

An electric bulb is filled with :

  1. hydrogen

  2. oxygen and hydrogen

  3. electrical energy

  4. nitrogen and argon
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Incandescent light bulbs are filled with an inert gas like nitrogen, argon, or krypton - so that the filament doesn't catch fire. Early ones were a vacuum. Flourecent lamps are filled with an inert gas plus mercury vapour or neon, which glows ultra-violet when charged. The inside of the bulb is painted to give it colour.

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

The filament of bulb offers ______ resistance to electric current.

  1. no

  2. low

  3. high

  4. very low
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The filament of bulb has high resistance so the filament heats up due to current passing through (${ I }^{ 2 }R$ losses )  and due to its heating , the electrons change their energy states and photons in visible spectrum are emitted . more the losses , more would be the light.that's why filament of bulb offers high resistance.

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

When current is passed through an electric bulb, its filament glows, but the wire leading current to the bulb does not glow because :

  1. Less current flows in the leading wire as compared to that in the filament

  2. The leading wire has more resistance than the filament

  3. The leading wire has less resistance than the filament

  4. Filament has coating of fluorescent material over it
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The leading wire is usually made with conductors such as copper and aluminium, therefore have less resistance than the filament which is usually made with tungsten and has a high resistance.
Due to this the power lost P $ =I^{2}R $ is greater for filament which is visible as light(and also heat).

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

The filament of a bulb is usually a

  1. Thin wire with many coils

  2. Thick wire with many coils

  3. Thin straight wire

  4. Thick strength wire
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Filaments in incandescent light bulbs are made of tungsten. 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 fine wire, also known as the coiled coil.

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

The material which is used as a filament for bulb has high ____________ .

  1. Boiling point

  2. Melting point

  3. freezing point

  4. pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The melting point of filament of a bulb is very high because the bulb begins to glow only when the filament is heated to a high temperature,and it becomes incandescent (bright) without melting.This happens only when the material of the filament has a high melting point.Hence, the material used in the filament of an electric bulb must have a high melting point. For example Tungsten
Multiple choice physics simple electric circuits bulbs bulb bulb connected to an electric cell

Which of the following is/are properties of filament of bulb?

  1. High melting point

  2. Low melting point

  3. Non-corrosive

  4. high temperature resistance
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation
The filament is an important part of incandescent lamp. The life of an incandescent lamp, depends on its filament. The filament material must have following merits-
  1. High melting point.
  2. Low vapor pressure.
  3. Free from oxidation in inert gas (i.e. argon, nitrogen etc.) medium at operating temperature.
  4. High resistivity.
  5. Low thermal coefficient of expansion.
Multiple choice physics simple electric circuits bulbs bulb bulb connected to an electric cell

Which of the following things can be used as a filament of electric bulb?

  1. Tungstan

  2. Tin

  3. Lead

  4. Steel
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Tungsten metal is selected for making filaments of lamp bulbs because tungsten can sustain high temperatures and it has high melting point, combined with the fact that it also has high resistivity. They do not oxidize easily at high temperatures.

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

Which of the following will create breaking of filament of a bulb?

  1. Large current flowing through filament

  2. Less current flowing through filament

  3. Corrosion from air

  4. Expansion because of heat produced
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Large current flowing through filament,Expansion because of heat produced will create breaking of filament of a bulb
The filament heats and gives off light. Over time, the filament oxidizes and becomes more and more brittle, until it breaks apart and the bulb goes out. ... Tungsten gains resistance as it heats. Resistance is the amount of 'push back' a material has against an electric current

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

A 25W and 100W bulb are joined in series and connected to the mains. Which bulb will glow brighter?

  1. 25 W bulb

  2. 100 W bulb

  3. Both bulb will glow brighter

  4. None will glow brighter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Resistance of 25 w bulb, ${R _1} \Rightarrow \frac{{{{220}^2}}}{2} = 1936\Omega $

$\begin{array}{l} { R _{ 2 } }=\frac { { { { 220 }^{ 2 } } } }{ { 100 } } =484\Omega  \ In\, \, series \ P\alpha R, \end{array}$
25 w will glow more