Answer:
[tex]B = 1.03 \times 10^{-4} T[/tex]
Explanation:
As we know that magnetic force on a moving charge is given by the formula
[tex]F = q(\vec v \times \vec B)[/tex]
so we will have
[tex]F = qvBsin\theta[/tex]
now we will have
[tex]F = 4.6 \times 10^{-3} N[/tex]
[tex]q = 8.1 \mu C[/tex]
[tex]\theta = 50^o[/tex]
[tex]v = 7.2 \times 10^6 m/s[/tex]
now we have
[tex]4.6 \times 10^{-3} = (8.1 \times 10^{-6})(7.2 \times 10^6)Bsin50[/tex]
[tex]B = 1.03 \times 10^{-4} T[/tex]