The speed of electrons in a cathode ray beam ,which remains undeflected ,in Thomas experiment ,under the simultaneously action of a magnetic field `2xx10^(-3)Wbm^(-2)`and the of an electric field `3.4xx10^(4)Vm^(-1)`is

Options

A. `1.7xx10^(7)ms^(-1)`
B. `2.8xx10^(7)ms^(-1)`
C. `1.2xx10^(6)ms^(-1)`
D. `5.4xx10^(6)ms^(-1)`

Answer

A

Explanation

In the Thomoson expermint ,
Magnetic field ,`B=2xx10^(-3)Wb^(-2)`
Electric field ,`E=3.4xx10^(4)Vm^(-1)`
The expression for speed of beam of electron is given as,
Speed of electron
`(E)/(B) =(3.4xx10^(4))/(2xx10^(-3))=1.7xx10^(7)ms^(-1)`