Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: where do sparks hit?

Learn more physics!

Most recent answer: 06/13/2017
Q:
We know that in gas lighter used to light a stove in the kitchen, spark is produced by piezoelectric effect. The Anode is in the form of a rod and the cathode is a cylinder. My question is, is the spot where the spark hits the cathode random ? (Since cathode is circular,the spark has equal probability of hitting any where on the circle) or is it dependent on any other factor.
- Rakesh Khanna (age 26)
Bangalore, India
A:

My guess is that the cathode will have small bumps and scratches on it, like any ordinary piece of metal that hasn't been specially polished. At the tip of a bump the electric field will be especially strong. So the spark should probably go to the tip with the strongest field, which will depend on how big the bump is and how sharp the tip is. The sparks themselves are likely to disrupt the tips so that the spot may wander around.

Mike W.


(published on 06/13/2017)

Follow-up on this answer.