Magnetic Effects Of Current Question 408
Question: A 10 eV electron is circulating in a plane at right angles to a uniform field at magnetic induction $ {{10}^{-4}}Wb/m^{2} $ (=1.0 gauss). The orbital radius of the electron is
Options:
A) 12cm
B) 16cm
C) 11cm
D) 18cm
Show Answer
Answer:
Correct Answer: C
Solution:
[c] K.E. of electron= $ 10,eV\Rightarrow \frac{1}{2}mv^{2}=10,eV $
$ \Rightarrow \frac{1}{2}(9.1\times {{10}^{-31}})v^{2}=10\times 1.6\times {{10}^{-19}} $
$ \Rightarrow v^{2}=\frac{2\times 10\times 1.6\times {{10}^{-19}}}{9.1\times {{10}^{-31}}} $
$ \Rightarrow ,v^{2}=3.52\times 10^{12}\Rightarrow v=1.88\times 10^{6}m $ Also, we know that for circular motion $ \frac{mv^{2}}{r}=Bev\Rightarrow r=\frac{mv}{Be}=11,cm $
BETA
