1) An electron moves at right angle to a magnetic field of $5 \times 10^{-2}T$ wirth speed of $6 \times 10^{7}m/s$ .If the specific charge orf the electrons is 1.7$\times 10^{11}$C/kg .The radius of the circular path will be A) 2.9 cm B) 3.9 cm C) 2.35 cm D) 2 cm Answer: Option CExplanation:Radius of circular path $r=\frac{mV}{B}=\frac{V}{\left(\frac{e}{m}\right)B}$ $r=\frac{6\times 10^{7}}{1.7\times 10^{11}\times15\times 10^{-2}}$ $=2.35 \times 10^{-2}$m=2.35 m
