Q32 of 91 Page 230

An electron having a kinetic energy of 100 eV circulates in a path of radius 10 cm in a magnetic field. Find the magnetic field and the number of revolutions per second made by the electron.


Given-
Kinetic energy of an electron = 100 eV



Radius of the circle = 10 cm


We now kinetic energy is given by



Where


From question , we can confer that




Here,
m is the mass of an electron


v is the velocity of an electron.


We know that 1 eV = 1.6 × 10−19 J


Thus,






Now, radius r -








Therefore, magnetic field applied is 3.4 × 10−4 T



Number of revolutions per second of the electron is nothing but the frequency given by ,




From (1)











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