Question

If electron is moving along x axis and at some point V is 5x+3,then it
a) Deflects up
b) Deflects down
c) Speeds up
d) Speeds down

Answer 1

@sidsiddhartha any idea ?

Answer 2

another thing is as the point V value is added up in magnitude so i think there will be no deflection so most obvious answer could be=speed up
but not sure

Answer 3

what do u think?

Answer 4

No idea about this one . no getting the ques :/

Answer 5

@Vincent-Lyon.Fr he can help u

Answer 6

If proton is moving along negative x axis, V is 2y-5, then it
a) Deflects up
b) Deflects down
c) Speeds up
d) Speeds down

One more like this
Confused in both :/

Answer 7

@Rohitkhanna @matricked @nincompoop @hartnn @kropot72 @arabpride

Answer 8

Do you know how to go from potential to electric field?

Answer 9

I think No , I don't :/

Answer 10

electric field decreases in the direction of increasing potential.electric potential is the work required to bring a unit positive charge from infinity to a point in the electric field.
more the electric field at a point,less is the work required to move the charge in its direction.

Answer 11

So what would be the answer ??

Answer 12

in the first ques., V=5x+3
it is clear from above equation that potential is increasing in the positive x-direction and the electric field is directed towards the negative x-direction.
an electron is negatively charged so force will act on it in the oppoite direction of electric field.therefore it will speed up.

Answer 13

ok So in second one in case of proton, speed down ???

Answer 14

first tell me what is the direction of electric field in second ques,i.e.along which axis is the electric field?

Answer 15

in second case potential is decreasing along y-axis .

Answer 16

yes.so the electric field increases as we move upward on the y-axis.
the proton is moving along x-axis.this implies that electric field is perpendicular to the motion of proton,so force will act on proton along positive y-axis,perpendicular to it.

Answer 17

SO its deflect upward ?

Answer 18

yes.correct.

Answer 19

Thank you so much @Rohitkhanna ya explained so well . everything make clear to me . Thanks a bunch . :d ^_^

Answer 20

ur welcome.

Answer 21

Positive particles are attracted to low potentials.
Negative particles are attracted to high potentials.

So one of the answers is wrong.

Answer 22

both r correct. @Vincent-Lyon.Fr
in first ques,electron is speeding up in the positive x-direction and potential is also increasing in the same direction.
in second ques,proton is delected up and potential is also decreasing in the upward direction.
so although what u said is correct about potential and charges,the answes r right.

Answer 23

No, in the second question, potential is V(x,y) = 2y - 5
so it is increasing in the y direction.

Answer 24

So what is answer for 2nd one ? @Vincent-Lyon.Fr

Answer 25

oh yes.sorry I misread the equation in second question.
potential increases in the positive y-direction and therefore electric field increases in the negative y-direction.
so the proton deflects in the direction of increasing electric field,i.e.it deflects downward.

Answer 26

but how potential is increasing ? @Rohitkhanna how we get to know from V = 2y - 5 ???

Answer 27

V=2y-5
as u put values of y,u get corresponding values of potential(V).for example when y=2 then V=-1,when y=5 then V=2(5)-5=5.
as we increase the y-coordinate,V increases and electric field decreases.
Hence we can conclude that Potential is increasing in upward direction and electric field is increasing in downward direction.

Answer 28

oh I see . Can ya give me example of negative one ? I mean decreasing potential as in both potential is increasing in that particular direction .

Answer 29

if equation like this V = -2y-5 then it decreasing toward Y axis right ?

Answer 30

u can write a equation for that.
for example if we write V=4-5x.
In this case as we keep increasing the values of x,V gets more and more negative,i.e.it decreases in the positive x-direction.
ur example is also right.

Answer 31

thank you so much @Rohitkhanna It helps me a lot . Thanks a bundle ^_^

Answer 32

your welcome.