Question

Sensitive instruments can detect the passage of as few as 60 electrons/s. To what current does this correspond?

Answer 1

Answer:

$9.6\cdot 10^{-18} A$

Explanation:

Current is defined as

$I=\frac{Q}{t}$

where

Q is the charge passing through a given point

t is the time interval

The SI unit of the current is the Ampere (A), where

$1A = 1C/s$

which means 1 Ampere is 1 Coulomb per second.

The charge of 1 electron is (in magnitude)

$e=1.6\cdot 10^{-19}C$

So, the charge of 60 electrons is

$Q=Ne=(60)(1.6\cdot 10^{-19})=9.6\cdot 10^{-18} C$

Therefore, if there are 60 electrons passing per second, the current is

$I=\frac{9.6\cdot 10^{-18} C}{1 s}=9.6\cdot 10^{-18} A$