# What speed do the electrons have when they strike the screen?

1. Nov 15, 2009

### S1CkFiSh

In a typical color television tube, the electrons are accelerated through a potential difference of 25,000 Volts. What speed do the electrons have when they strike the screen? (qe = 1.6 x10-19 C, me = 9.1 x10-31 kg)

2. Nov 15, 2009

### mgb_phys

What is the energy to move a charge through a voltage?
Then if no energy is lost this becomes kinetic energy

3. Nov 15, 2009

### S1CkFiSh

These are the possible answers.
a. 0.55c.
b. 0.09c.
c. 0.30c.
d. 0.90c.

4. Nov 15, 2009

### mgb_phys

I know the answer - the point is for you to learn something

5. Nov 15, 2009

### S1CkFiSh

I don't know what formula to use.

6. Nov 15, 2009

### mgb_phys

You need an equation with voltage, charge and energy - have you come across electron-volt?

Do you know the equation for kinetic energy?

7. Nov 15, 2009

### S1CkFiSh

No, I just need the exact formula then I will know what to do from there.

8. Nov 15, 2009

### SrEstroncio

Dude, just open the nearest physics book available and go to the section on voltage differences between two points in space, you'll know which formula to use right away

You can even google it.