Why Do Light Bulbs Blow When You Turn Them On?

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SUMMARY

Light bulbs typically blow when turned on due to the high current passing through the filament, which is a result of low resistance at lower temperatures. As the filament heats up, its resistance increases, but the initial surge of current can exceed the filament's capacity, leading to failure. The mechanical strain caused by thermal expansion also contributes to the filament's breakage. Understanding the relationship between resistance, temperature, and current is crucial in explaining this phenomenon.

PREREQUISITES
  • Basic understanding of electrical resistance
  • Knowledge of Ohm's Law
  • Familiarity with the properties of metals and temperature effects
  • Concept of thermal expansion in materials
NEXT STEPS
  • Research the relationship between temperature and resistance in metals
  • Study Ohm's Law and its applications in electrical circuits
  • Explore the concept of thermal expansion and its effects on materials
  • Investigate the design and materials used in light bulb filaments
USEFUL FOR

Students studying physics, electrical engineers, and anyone interested in the principles of electrical resistance and thermal dynamics in light bulbs.

_Muddy_
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Homework Statement



We did an experiment in class abvout resistance and temperature. The teacher told us to find out why light bulbs usually blow when you turn on the light. It must be related to the experiment we did which was seeing how resistance changed with temperature

Homework Equations


I'm not sure if there are any, If there are please tell me


The Attempt at a Solution


I have no idea why, and i wouldn't know where to look on the internet

thanks

_Muddy_
 
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The light bulb fails because the current through the filament is too large.
The current depends on the resistance
How does the resistance of metal change with temperature ?
 
mgb_phys said:
The light bulb fails because the current through the filament is too large.
The current depends on the resistance
How does the resistance of metal change with temperature ?

The higher the temperature the higher the resistance.

So then, the light bulb fails because the current through the filament is too large. The resistance is too low. So the temperature is too high. Is that correct? What actually happens to the filament, does it break? Why would a high temperature/ high current make the light bulb fail?
 
The filament is a thin metal wire - rather like a fuse.
When the filament is cold the resistance is lower and so the currentis higher.

The current heats the wire which expands which puts a mechanical strain on it.
Also when the light is first turned on is the greatest temperature difference and so the greatest strain - this is probablyy more important than the resistance in reality
 
thanks a lot for that, I'm pleased and my teacher should be pleased aswell
 

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