The current intensity is the product between the total charge that flows through a certain point (in our case, the target) in a time interval [tex]\delta t[/tex]:
[tex]I= \frac{Q}{\Delta t} [/tex]
We know the current, [tex]I=130 \mu A=130 \cdot 10^{-6} A[/tex], and the time interval, [tex]\Delta t=17 s[/tex], so we can find the total charge:
[tex]Q=I \Delta t= 2.21 \cdot 10^{-3}C
[/tex]
The total charge Q is the product between the number of protons N and the charge of each protons, e, which is [tex]e=1.6 \cdot 10^{-19}C[/tex]:
[tex]Q=Ne[/tex]
we can re-write the equation solving for N, so we can find the number of protons striking the target in 17 s:
[tex]N= \frac{Q}{e}= \frac{2.21 \cdot 10^{-3}C}{1.6 \cdot 10^{-19}C} =1.38 \cdot 10^{16} [/tex]
