Question

When you touch a friend after walking across a rug on a dry day, you typically draw a spark of about 1.98 mm. Calculate the potential difference between you and your friend just before the spark. (The magnitude of the electric field for which dielectric breakdown occurs in air is about 3.0 MV/m.)

Answer 1

To solve this problem we will apply the concept of potential difference defined as the product between the electric field and distance, that is

`V = E \Delta l`

Here,

E = Electric Field

`\Delta l` = Length

Our values are,

`E = 3MV/m`

`l = 1.98*10^(-3) m`

Replacing,

`V = (3 MV/m)( 1.98*10^(-3) m)`

`V= 5.94*10^(-3) MV`

`V = 5940V`

Therefore the difference potential between you and your friend just before the spark is 5940V