Difference between revisions of "Electrical Bulb"
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: In a [[Filament Bulb|filament]] '''bulb''' [[Electrical Work|electrical work]] is done to [[heat]] the filament to a high enough [[temperature]] that it glows in [[Visible Light|visible light]], see [[Black Body Radiation|black body radiation]]. | : In a [[Filament Bulb|filament]] '''bulb''' [[Electrical Work|electrical work]] is done to [[heat]] the filament to a high enough [[temperature]] that it glows in [[Visible Light|visible light]], see [[Black Body Radiation|black body radiation]]. | ||
: The [[Electrical Current|electrical current]] has a [[heating]] effect on the filament which increases its [[temperature]]. This causes the [[Electrical Resistance|resistance]] to increase, so the '''bulb''' does not behave as an [[Ohmic Conductor|ohmic conductor]]. | : The [[Electrical Current|electrical current]] has a [[heating]] effect on the filament which increases its [[temperature]]. This causes the [[Electrical Resistance|resistance]] to increase, so the '''bulb''' does not behave as an [[Ohmic Conductor|ohmic conductor]]. | ||
| + | |||
| + | ===IV Graph=== | ||
| + | {| class="wikitable" | ||
| + | |- | ||
| + | |[[File:IVGraphBulb.png|center|400px]] | ||
| + | |- | ||
| + | | style="height:20px; width:200px; text-align:center;" | | ||
| + | |} | ||
| + | ====Description==== | ||
| + | The [[IV Graph]] for a '''bulb''' shows that: | ||
| + | *As [[Potential Difference|potential difference]] increases, [[Electrical Current|increases]]. | ||
| + | *At small [[Potential Difference|potential differences]]] the the relationship between [[Potential Difference|potential difference]] and [[Electrical Current|current]] is [[linear]] (the [[gradient]] is constant). | ||
| + | *At large [[Potential Difference|potential differences]] the [[gradient]] becomes more shallow as the [[Electrical Resistance|resistance]] of the '''bulb''' increases. | ||
| + | |||
| + | ====Explanation==== | ||
| + | : At small [[Potential Difference|potential differences]] there is a small [[Electrical Current|current]] so the [[heating]] effect of the [[Electrical Current|current]] is small and the [[filament]] remains at a low [[temperature]]. | ||
| + | : At large [[Potential Difference|potential differences]] there is a large [[Electrical Current|electrical current]] so the [[heating]] effect of the [[Electrical Current|current]] is large which causes the [[filament]] to be a high [[temperature]]. | ||
| + | :: This is caused by [[electron]]s in the [[wire]] [[collide|colliding]] with [[ion]]s in the [[metal]] [[lattice]] causing them to [[vibrate]]. | ||
| + | : [[Wire]]s (like the [[filament]]) have a greater [[Electrical Resistance|resistance]] at higher [[temperature]]s, causing the increase in [[Electrical Current|current]] to be reduced. | ||
| + | :: This is because the more the [[ion]]s in the [[metal]] [[lattice]] [[vibrate]] the more likely [[electron]]s are to [[collide]] with them and slow down. | ||
Revision as of 14:53, 28 February 2019
Contents
Key Stage 1
Meaning
This bulb has a filament inside it that glows when electricity goes through it.
A light bulb is something that lights up when you switch it on.
Key Stage 2
Meaning
An electrical bulb is a circuit component that gives out light when electricity goes through it.
About Electrical Bulbs
- There are many different kinds of electrical bulb.
- The type of electrical bulb you will use in class is called a Filament Bulb. It has a thin piece of wire inside that glows when electricity passes through it.
- Electrical bulbs can get very hot so you shouldn't touch the glass.
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 |
| An electrical bulb. | The symbol for an electrical bulb. |
Key Stage 3
Meaning
An electrical bulb is a circuit component that gives out light when electricity goes through it.
About Electrical Bulbs
- There are many different kinds of electrical bulb.
- The type of electrical bulb used in class is called a Filament Bulb. It has a thin piece of wire called a filament that becomes so hot when electricity passes through it that it begins to glow.
- Electrical bulbs can get very hot so you shouldn't touch the glass.
|
|
| An electrical bulb. | The symbol for an electrical bulb. |
Key Stage 4
Meaning
An electrical bulb is a circuit component that gives out light when electricity goes through it.
About Electrical Bulbs
- An electrical bulb usually refers to a Filament Bulb. However, there are other types.
- In a filament bulb electrical work is done to heat the filament to a high enough temperature that it glows in visible light, see black body radiation.
- The electrical current has a heating effect on the filament which increases its temperature. This causes the resistance to increase, so the bulb does not behave as an ohmic conductor.
IV Graph
 |
Description
The IV Graph for a bulb shows that:
- As potential difference increases, increases.
- At small potential differences] the the relationship between potential difference and current is linear (the gradient is constant).
- At large potential differences the gradient becomes more shallow as the resistance of the bulb increases.
Explanation
- At small potential differences there is a small current so the heating effect of the current is small and the filament remains at a low temperature.
- At large potential differences there is a large electrical current so the heating effect of the current is large which causes the filament to be a high temperature.
- Wires (like the filament) have a greater resistance at higher temperatures, causing the increase in current to be reduced.