Question

A proton moves with a speed of $5.0\times 10^{6}m/s^{-1}$ along the $x$-axis. It enters a region where there is a magnetic field of magnitude $2.0$ tesla directed at an angle of $30^{\circ }$ to the $x$-axis and lying in the $xy$ plane. The magnitude of the magnetic force on the proton is

• A. $0.8\times 10^{-13}N$
• B. $1.6\times 10^{-13}N$
• C. $18\times 10^{-13}N$
• D. $8.0\times 10^{-13}N$
• E. $16\times 10^{-13}N$

Answer 1

Answer: (D)

Given,
The speed of proton,
$V=5.0\times 10^{6}m/s$
Magnetic field, $B=2.0$ Tesla angle $\theta =30^{\circ }$
Charge on proton, $q=1.6\times 10^{-19}C$
When the proton enters in magnitude field, it experiences Lorentz force
$F=q(v\times B)$
$|F|=qvB\sin \theta$
$F=1.6\times 10^{-19}\times 5\times 10^6\times 2\times \sin 30^{\circ }$
$=8.0\times 10^{-13}N$