A Level Physics: Electric Fields Practice Questions

[@zhelyo_physics]

Hey guys, there is a typo at 34:04, the formula for the volume of a sphere is of course V=4/3*pi*r^3 and the radius should be cubed. The value for the force should be given in N just before that too. The final answer is still correct and the subsequent working : )

[@ElHal04]

feeling more confident now. i still might need some luck tomorrow though lol. thanks as always!

[@zhelyo_physics]

Luck is always good! : ) Good luck! 😀

[@duo496]

same lmao

[@TinasheFPS]

was confused with this topic at first but after the walkthrough i sort of understand how to do most calculations now. All thanks to you sir

[@zhelyo_physics]

Amazing! Glad to hear, thank you so much for the comment!

[@ammxarr]

in question 5, while finding the Force the radius wasnt cubed neither was it squared, secondly the unit of force was written as kg, and thirdly you inserted that in Q=Fd/V equation so that was a bit confusing hopefully you can clear that up for me, i appreciate all of the work you put in for A level students thank you.

[@zhelyo_physics]

Thanks! There is a typo, the final answer is still correct though. Using the formula of the sphere V=4/3*pi*r^3. So because the droplet is stationary, the force mg is equal to the electrostatic force balancing it. This allows us to insert it into the electrical force, F=EQ, i.e. Q=F/E=F*d/V Hope this helps!

[@serenity7637]

5:03 can we use v^2=u^2+2as for this? i got 1 x 10^16

[@fatimamajeed1758]

At 35:43 shouldn't the anwer for Q be 1.1*10^-19 C ?

[@zhelyo_physics]

thanks for spotting, I double checked and I think I've made a typo. I'll add this to the description.

[@drneutro369]

Hi sir, these exam question videos are great! Do they cover most of the types of exam questions you could get for this topic?

[@zhelyo_physics]

They cover a lot of situations, however there will certainly be new ones for the real exams. Part of the exams is always designed to test the physics knowledge in new situations.

[@drneutro369]

Thanks! These exam questions are really helping me in my revision for my upcoming mocks

[@dianagrygorchuk8722]

Hi sir, in question 4 part (ii) would it be ok to use the formula work done=force * distance?

[@zhelyo_physics]

it would give the same answer. Generally using the fact that the gain in energy is eV is a lot easier typically though : )

[@AthensPlays]

i just finished the syllabus for physics what would you recommend me to do i have an exam on the 7th biology which i am covering the spec at the same time and 9th for physics so i lost alot of time for questions i was down around after the 24th and started on the 31st bc i was demotivated

[@mayagupta9948]

in the same position paper 1 was really rough and meant to be my best paper

[@saighazaidi316]

hi! in the Q1 graph of Ek against x why is the gradient, not zero till 0.04m since no vertical velocity and a constant horizontal velocity throughout?

[@zhelyo_physics]

excellent question. The wording is a bit tricky, it is asking you to sketch from the start of the region of the electric field.

[@saighazaidi316]

But isn't the electron already in the electric field when it is moving with a constant horizontal velocity?

[@zhelyo_physics]

yep, but kinetic energy is a scalar, i.e. the speed v =sqrt(v_x^2+v_y^2), so the y component starts increasing in the field and hence so does the speed.

[@saighazaidi316]

Okie thanks

[@saighazaidi316]

Also i love the way you teach! A request, please can you also cover A levels Alternating currents🥺

[@sas9454]

Hello, is there a reason you chose OCR?

[@ultraassassin393]

For Q2b how comes we don't have to divide by 2 since it asks for the force on each sphere?

[@gabrielharris9462]

The equation calculates the force on one sphere so you don't need to divide by 2

[@udayreddy3705]

Sir for q1vii the kinetic energy graph why does it not start at origin ?

[@zhelyo_physics]

so the particle comes in with some horizontal speed, which means it has some energy. The vertical speed is 0 and that increases but the particle already has horizontal speed and hence kinetic energy. Hope this helps!

[@meowwqq]

25:39 why isn’t Qq equal to 1.67*10^-27 * 1.6*10^-19 instead sir? really appreciate all the work you put in for us by the way 😊

[@zhelyo_physics]

Thanks a lot much appreciated! The charge of an electron and a proton are equal at 1.6*10^-19. Note: 1.67*10^-27 is instead the mass of a proton which we don't use for this calculation.

[@meowwqq]

@@zhelyo_physics thank you sir 😊

[@mujtabashafi3775]

In the 2nd question, can I multiply 2.8×10^-9 and 6.24×10^18. Answer is 1.7×10^10 will it still be correct

[@mujtabashafi3775]

Part a

[@zhelyo_physics]

But where did you get 6.24×10^18? To find the number of excess electrons just divide the total charge by the electron charge.

[@mujtabashafi3775]

@@zhelyo_physics number of electrons in 1 coulomb charge

[@zhelyo_physics]

@@mujtabashafi3775 you are basically using the same method. If you are doing A Levels though, you are not given that number.

[@elhaambasheerch7058]

Are these qs also relevant to students of International A level physics(9702) ?

[@zhelyo_physics]

Yes! Electric fields are the same regardless of exam boards, still make sure to practice using your board just to ensure you get all the details right.

[@nasifrahman4483]

sir why the video is shortened and cut at some parts?

[@zhelyo_physics]

I will investigate, I think I removed a question with a mistake

[@nasifrahman4483]

Ok sir

[@experimentalviews0]

hi sir, in q4 ii how is Ek equal to WD

[@zhelyo_physics]

so work done is in general equal to the change of energy. Hope this helps!

[@experimentalviews0]

@@zhelyo_physics what if we need to find Ep? will it be equal to WD too?