Sorry, my first post doesn't make it look like this because my m is not under the square root, but it should be - just an error with copy and paste. So I did do this, but I still feel lost. Is the equation I'm using applicable - the number's I've come up with don't seem right.
Assuming that the speed of the electrons is zero as they are emitted from the filament and that as they reach the anode it is v, find an expression relating the final speed v to the charge on an electron, the mass of an electron and deltaV, and hence calculate the speed v of the electrons after...