My book shows this diagram in which electron moving only in magnetic field (where direction of magnetic field is out of the page) going down (after affecting by magnetic field) and hitting at point 'B'(not applying electric current/field). But according to Fleming's left hand rule the electron should go up(force due to magnetic field should push it up) and should hit at point 'A' (as direction of current is opposite from that of electrons).
Here is the Fleming's left hand rule from my book
Best Answer
The picture in your book contains an error. The magnetic field has to go into the other direction. Otherwise the electric and magnetic force cannot cancel each other and thus the experimental setup would not make much sense.
You can find a correct visualization of the experiment in Experiment 3: Mass-to-charge (e/m) ratio
You can clearly see that the north and south pole are swaped compared to your picture, whereas the electric field remains unchanged.
Well done! You´ve applied the Fleming´s left-hand rule correctly.