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A proton beam in an accelerator carries a current of 130 μa. if the beam is incident on a target, how many protons strike the target in a period of 17.0 s?

User Remoo
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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
\delta t:

I= (Q)/(\Delta t)
We know the current,
I=130 \mu A=130 \cdot 10^(-6) A, and the time interval,
\Delta t=17 s, so we can find the total charge:

Q=I \Delta t= 2.21 \cdot 10^(-3)C

The total charge Q is the product between the number of protons N and the charge of each protons, e, which is
e=1.6 \cdot 10^(-19)C:

Q=Ne
we can re-write the equation solving for N, so we can find the number of protons striking the target in 17 s:

N= (Q)/(e)= (2.21 \cdot 10^(-3)C)/(1.6 \cdot 10^(-19)C) =1.38 \cdot 10^(16)
User Cooperia
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