In a Certain Particle Accelerator,a Current of 300 $\mu$ A Is Carried by a 4

Multiple Choice

In a certain particle accelerator,a current of 300 $\mu$ A is carried by a 4.00-MeV proton beam that has a radius of 1.30 mm.The mass of a proton is 1.67 $\times$ 10^-27 kg.What is the number of protons per unit volume in this beam?

A) 3.64 $\times$ 10¹³ protons/m³
B) 2.76 $\times$ 10¹³ protons/m³
C) 1.27 $\times$ 10¹³ protons/m³
D) 5.98 $\times$ 10¹³ protons/m³
E) 4.17 $\times$ 10¹³ protons/m³