How many electrons jump from your hand to the knob?

Just as you touch a metal door knob, a spark of electricity (electrons) jumps from your hand to the knob. The electric potential of the knob is 1.0 ✕ 10^4 V greater than that of your hand. The work done by the electric force on the electrons is 1.5 ✕ 10^-7J.

1 Answer
Jan 24, 2016

approx 9.363xx 10^79.363×107

Explanation:

If WW is the work done for moving a charge QQ from a location A having Potential V_AVA to another location B having Potential V_BVB, then the expression between these quantities is given as

Delta V=V_B-V_A=Work done in moving the charge/Q

Inserting the given values we get
Q=(1.5 times 10^-7)/(1xx10^4)C
The value of electric charge on an electron, e^- = 1.6021 xx 10^-19C
We obtain number of electrons transferred from hand to the knob by dividing Q with e^-

N_e=(1.5 times 10^-7)/(1xx10^4)xx1/(1.6021 xx 10^-19)
N_eapprox 9.363xx 10^7