00:01
All right, so in this problem, so we place an electron into the electric field, and this electron move upward, sorry, move upward, this is a bad arrow.
00:19
And it travels 4 .5 meters in, let me see, three microseconds.
00:25
So we want to find out the magnitude of the electric field and the direction.
00:30
So firstly, because the electron is moving upward, so basically the force is moving upward, so the electric field has to be pointing down because the electron carry negative charge, right? and then we are looking at the magnitude.
00:49
So because initially the electron is at rest, so we can see that half a t squared is the distance that it traveled equal 4 .5 meters.
01:01
And t here equal 3 microseconds.
01:04
And if you solve this equation, you can see that a equal 10 to the 12 meters per second squared.
01:14
So, and according to newton's law, a equal f over m, right? and f is here, we're just looking at the electric force.
01:26
So f equal to e times q, we should use small e...