Oxford PAT 2015 example question 11

2015_1_page2

3 thoughts on “Oxford PAT 2015 example question 11

  1. Are you sure you can simply use t=(d/u)? The electron is being accelerated across the potential difference, so its not constant velocity, which is why I feel you cannot use that eqn. The u that you have used the is maximum velocity, but it starts from 0 and accelerates to that velocity. It was not travelling at that velocity the whole time.

    1. If the velocity were not constant your point would be absolutely right, but the velocity is constant for the journey between the gun and the screen, which is what my diagram covers. The question says that the screen is 0.4m away from the electron gun, which means that the screen is 0.4m away from the electron when it comes out of the gun, by which time its acceleration is complete.

      This question is not helpfully worded. It should really say (1) the electron is accelerated by a voltage of 50V in an electron gun, and then (2) the electron travels a distance of 0.4m to a screen.

Add your comments

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s