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# Cathode ray tube quick question. watch

1. Hi,

I've been doing this sheet about cathode ray tubes. I'm a bit stuck on question 8 part 1, where it says use the velocity you calculated in part 5 to work out the time taken between the cathode and the anode. It says to work out the average velocity as the electron is accelerating but I'm not sure how to do this.

Thanks
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3. (Original post by VioletPhillippo)
It means assume constant acceleration and rearrange the suvat
s=1/2(u+v)t

to make t the subject

you could think of calculating 1/2(u+v) as being the average velocity
4. (Original post by Joinedup)
It means assume constant acceleration and rearrange the suvat
s=1/2(u+v)t

to make t the subject

you could think of calculating 1/2(u+v) as being the average velocity
Thanks, so using suvat rather than speed=distance/time as there is acceleration but it is assumed constant?
5. (Original post by VioletPhillippo)
Thanks, so using suvat rather than speed=distance/time as there is acceleration but it is assumed constant?
I think you'll assume the electrons are accelerated from rest to their final energy over the distance between the cathode and the anode... it'd be a constant acceleration for realistic CRTs as used in old televisions etc.

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