j.j.thomson's expt (1 Viewer)

[rnitya_25]

hi,
jj thomson did an expt to measure the charge/mass ratio of an electron, can anyone explain it in a paragraph....every source i look at, its like a page of writing...doesn't register in my head....!! what did he do? and how did he do it?

 

[FinalFantasy]

Thomsom's famous achievement lay in the construction of special cathode ray tubes which he used to measure the ratio of the charges to mass for the electron. (e/ m). Thomson's experiment in 2 steps.
Step 1- Balance the magnetic field force with the electric field force so that the beam remains undeflected. Equate F(B) with F(E) to get v=E/B
Step2-Apply the magnetic field only. This results in circular motion. Knowing v and measuring radius of circle, produces an expression for the ratio e/m for the electron.
The final outcome of the Thomson experiment was measurement of e/m.

 

[rnitya_25]

wow, thanks alot!

 

[NoOb_ceNtRAL]

ya wat final fantasy said n also he didnt know value of E so he compared it to charge of proton. but it waz heapz larger (like 1800x)
so he said it couldnt be a wave (too slow) and it cant be proton (too light). they didnt know of electrons before then.
koolz, dats wat i undastood frm it

 

[NoOb_ceNtRAL]

hi ranjani!

 

[rnitya_25]

hi (if i knew who you were, id say your name)...sory.....identify yourself!!!! hehehe....thanks