Calculating Maximum Magnetic Force on Electrons in a Television Set

[thompson.1674]

magnetic force help ?

Homework Statement

In a television set, electrons are accelerated from rest through a potential difference of 23 kV. The electrons then pass through a 0.27 T magnetic field that deflects them to the appropriate spot on the screen. Find the magnitude of the maximum magnetic force that an electron can experience.

Homework Equations

.5mv^2
qvbsin=F

The Attempt at a Solution

So this is what i have done but its not right:
23000=.5(9.11E-31)V^2
V=2.247E17
(1.6E-19)(2.247E17)(.27)=.00968 N

But is is not correct.
Can anyone help me out?

 

[rock.freak667]

Kinetic energy=pd*charge of electron.

 

[alphysicist]

Hi thompson,

Homework Statement

In a television set, electrons are accelerated from rest through a potential difference of 23 kV. The electrons then pass through a 0.27 T magnetic field that deflects them to the appropriate spot on the screen. Find the magnitude of the maximum magnetic force that an electron can experience.

Homework Equations

.5mv^2
qvbsin=F

The Attempt at a Solution

So this is what i have done but its not right:
23000=.5(9.11E-31)V^2

I don't believe this is correct. For the energy equation, you'll need the potential energy change on the left; do you see what you have instead? Notice that it does not have the right units.

V=2.247E17

The upper limit on the possible speed would be the speed of light in a vacuum, which is a bit under 3E8 m/s, and so right away you know that can't be correct. That's an important thing to keep in mind when you do problems that involve these huge numbers.

(1.6E-19)(2.247E17)(.27)=.00968 N

But is is not correct.
Can anyone help me out?

 

[thompson.1674]

okay i see what i did and i have the right answer. thanks for your help