Magnetic Effects Of Current Question 361
Question: An electron (mass = $ 9.1\times {{10}^{-31}} $ kg; charge = $ 1.6\times {{10}^{-19}} $ C) experiences no deflection if subjected to an electric field of $ 3.2\times 10^{5} $ V/m, and a magnetic fields of $ 2.0\times {{10}^{-3}} $ Wb/m2. Both the fields are normal to the path of electron and to each other. If the electric field is removed, then the electron will revolve in an orbit of radius [BCECE 2005]
Options:
A) 45 m
B) 4.5 m
C) 0.45 m
D) 0.045 m
Show Answer
Answer:
Correct Answer: C
Solution:
For no deflection in mutually perpendicular electric and magnetic field $ v=\frac{E}{B}=\frac{3.2\times 10^{5}}{2\times {{10}^{-3}}}=1.6\times 10^{8},m/s $ . If electric field is removed then due to only magnetic field radius of the path described by electron $ r=\frac{mv}{qB}=\frac{9.1\times {{10}^{-31}}\times 1.6\times 10^{8}}{1.6\times {{10}^{-19}}\times 2\times {{10}^{-3}}}=0.45,m $
BETA
