Answer:
[tex]\mathbf{V_d = 3.2 \times 10^5 \ m/s}[/tex]
Explanation:
[tex]\text{The speed of the protons can be estimated by using the formula:}[/tex]
[tex]V_d = \dfrac{I}{enA}[/tex]
[tex]where;[/tex]
[tex]\text{e = proton charge}[/tex]
[tex]\text{n = No. of protons per unit volume}[/tex]
[tex]\text{A = area of aperture}[/tex]
[tex]V_d = \dfrac{91 \times 10^{-9} \ A}{(1.602 \times 10^{-19} \ C (7.0 \times 10^6 \ m^{-3} ) (\pi) (0.284 \ m)^2}[/tex]
[tex]\mathbf{V_d = 3.2 \times 10^5 \ m/s}[/tex]