In a TV picture tube electrons are ejected from the cathode with negligible speed and reach a velocity of `5x10^6` m/s in travelling one centimeter. Assuming straight line motion, find the constant force exerted on the electron. The mass of the electron is `9.1xx10^-31` kg.

Explanation

Given, Initial velocity, u=0 (negligible),
`v= 5xx10^6 m/s`
` S=1cm 1xx 10^-2 m`
`:. Aceleration, a= (v^2-u^2)/(2S)`
` =((5xx10^5)^2-0)/(2xx1xx10^-3)`
(25xx10^1)/(2xx10^02)`
`=12.5xx10^14 m/s^2`
And Force, F=ma
`=9.1xx10^-31xx12.5xx10^-14`
`=113.75xx10^-12` ltBrgt ` =1.1xx10^-15 N`.