Solving a Physics Problem: Electric Spark Distance Calculation

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SUMMARY

The discussion centers on calculating the distance at which an electric spark can occur between a charged hand and a metal doorknob, given a charge of Q=50 nanoC. The dielectric strength of air is stated as 3 kV/mm, indicating that a potential difference (pd) of 3 kV will generate a 1 mm spark. To estimate the pd between the human body and the doorknob, one must consider the capacitance of the human body and the geometry of the hand as an electrode. This problem requires making several assumptions about the physical parameters involved.

PREREQUISITES
  • Understanding of electric charge and capacitance
  • Knowledge of dielectric strength of materials, specifically air
  • Familiarity with basic physics equations related to electric potential and spark formation
  • Ability to make assumptions based on physical properties and geometry
NEXT STEPS
  • Research the formula for calculating electric potential (V = Q/C) and its application in this context
  • Study the dielectric strength of various materials beyond air for comparative analysis
  • Learn about the capacitance of the human body and factors affecting it
  • Explore the impact of electrode shape on electric discharge phenomena
USEFUL FOR

Students in physics, electrical engineers, and anyone interested in understanding electric discharge phenomena and spark formation in practical scenarios.

WilliamVeregg
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I'm totally stuck on a physics problem. I've been looking through my notes and my book for the past hour and cannot find anything.

The question is

Find the distance at which an electric spark would arise between your hand and the metal doorknob if your hand carries a total charge of Q=50nanoC

Is there an equation to solve this? I've tried googling this also.
 
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This has to be open ended and you need to make a number of assumptions.
The dielectric strength of air is approximately 3 kV/mm. In other words, a pd of 3kV will produce a 1mm spark.
You need to estimate the pd between your body (hand) and the door knob. (Take the door to be zero)
Can you find an estimate for the capacitance of the human body?
If so, one estimate would involve using this and the charge given to find V.
However, the shape of the electrode (your hand) also plays an important role.
 

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