# Potential Difference and spark plug

1. May 24, 2010

### CFrazzle

A spark plug in a car has electrodes separated by a gap of 0.025inches. To create a spark and ignite the air-fuel mixture in the engine, an electric field of 3.0 x 106 V/m is required in the gap. (a) What potential difference must be applied to the spark plug to initiate a spark? (b) If the separation between electrodes is increased, does the required potential difference increase, decrease, or stay the same. (c) Find the potential difference for a separation of 0.050”

delta V= -E delta s

E=Kq/r^2

r = distance
s = distance
delta V= potential difference
E=electric field intensity
K=9.0x10^9
q= charge

ive done the a section easy enough, but i have some questions about the b/c sections.
because the electrodes are seperating, will that also effect the electric field intensity.

2. May 25, 2010

### ehild

Read the question: It is about the required potential difference - required to create a spark. "To create a spark, an electric field of 3.0 x 106 V/m is required in the gap." So what about the electric field intensity?

ehild

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