A beam of protons moving with a velocity of `4 xx 10^(5) m/s` enetrs a uniform magnetic field of 0.3 T at an angle of 60◦ with the magnetic field. What is the radius of the helical path described by the proton beam?`[m_p=1.67 xx 10^(-27) kg` and the charge on the proton`=1.6 xx 10^(-19)`C]

Options

A. `10^(-2)m`
B. `1.2 xx 10^(-2)m`
C. `1.5 xx 10^(-2)m`
D. `2.5 xx 10^(-2)m`

Answer

B

Explanation

The radius of the helicasl path described by the proton beam is given by `r=(mvsintheta)/(Bq)=(1.76 xx 10^(-27) xx 4 xx 10^(5) xx sin60)/(0.3 xx 11.6 xx 10^(-19))=1.2 xx 10^(-2)m`.