Question

After walking across a dry carpet, there's a potential difference of 4400 V between your hand and the doorknob. As you reach toward the knob, a spark jumps, releasing energy 1.0 μJ .

Answer 1

You only wrote the statement of the problem, but I found some questions that I think are what you want:

a.- How much charge was transferred?

The charge can be calculated with this expression for energy:

Where q is charge and V is voltage. So:

$q = \frac{E}{V}$

$q = \frac{1x10^{-6}J}{4400v}$

ANSWER

b.- Assuming all the charges were electrons, how many were there?

Charge is given by:

$n = \frac{q}{e}$

$n = \frac{2.27x10^{-10}C}{1.602x10^{-19}C}$

ANSWER

I hope it helps!!