Join TSR now and get all your revision questions answeredSign up now

A-Level Physics - [Question]

    • Thread Starter
    Offline

    3
    ReputationRep:
    How many electrons flow past a point each second in a 5.0mA electron beam?
    I used I=Q/T
    I = 0.005 A
    Q =
    T = 1
    so Q = 0.005 C
    right?
    Online

    2
    ReputationRep:
    That seems correct.
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by JustasB)
    That seems correct.
    I got the answer it was just telling me it was wrong as I had
    3.13 instead of 3.1

    Thanks
    Online

    2
    ReputationRep:
    (Original post by AdeptDz)
    I got the answer it was just telling me it was wrong as I had
    3.13 instead of 3.1

    Thanks
    The answer was to 2 significant figures, so the answer of 3.13 is correct but it should be rounded to the correct number of significant figures.
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by JustasB)
    The answer was to 2 significant figures, so the answer of 3.13 is correct but it should be rounded to the correct number of significant figures.
    Thanks
    Do you have an idea on this question:
    Alpha particles have twice the charge of an electron. What is the current caused by a radioactive source which emits 3000 alpha particles per second, to 3 significant figures?

    First I found out the charge which is 3.2*10^-19 (For one alpha particle) then I multiplied it by 3000 to get charge for 3000 alpha particles which is 9.6x10^-16 C now i used I = Q/T
    so I would equal 9.6 x 10^-16 aswell but i'm not sure what to do now or what i done wrong as this answer is incorrect
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by AdeptDz)
    Thanks
    Do you have an idea on this question:
    Alpha particles have twice the charge of an electron. What is the current caused by a radioactive source which emits 3000 alpha particles per second, to 3 significant figures?

    First I found out the charge which is 3.2*10^-19 (For one alpha particle) then I multiplied it by 3000 to get charge for 3000 alpha particles which is 9.6x10^-16 C now i used I = Q/T
    so I would equal 9.6 x 10^-16 aswell but i'm not sure what to do now or what i done wrong as this answer is incorrect
    oh wow, it is correct just not to 3 sig. fig. once again.
    Keep making the same mistake, my bad!

    Edit:
    Do you know if i have to always use correct sig. fig. in the exam? (AQA if it helps)
    Online

    2
    ReputationRep:
    (Original post by AdeptDz)
    oh wow, it is correct just not to 3 sig. fig. once again.
    Keep making the same mistake, my bad!

    Edit:
    Do you know if i have to always use correct sig. fig. in the exam? (AQA if it helps)
    Use the same number of significant figures as given in the question.
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by JustasB)
    Use the same number of significant figures as given in the question.
    okay thanks
    Offline

    1
    ReputationRep:
    Did you get these questions on Isaac physics because I have been set this board and I literally have no clue! Hell
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by Mossie99)
    Did you get these questions on Isaac physics because I have been set this board and I literally have no clue! Hell
    Ye I did ; was a while back though


    Posted from TSR Mobile
    Offline

    1
    ReputationRep:
    (Original post by AdeptDz)
    Ye I did ; was a while back though


    Posted from TSR Mobile
    Found out I was doing the same mistake as you with my sig figs! Gets very frustrating when it continuously says incorrect! Thanks anyway
    Offline

    0
    ReputationRep:
    (Original post by AdeptDz)
    I got the answer it was just telling me it was wrong as I had
    3.13 instead of 3.1

    Thanks
    How did you get the answer of 3.13? I've tried for a while but can't get it.
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by Elementa)
    How did you get the answer of 3.13? I've tried for a while but can't get it.
    Charge / Charge on an electron
    0.005/1.6x10^(-19)
    I'm guessing that is what I done
    and that gives you 3.13x10^16

    Sorry for the late reply
 
 
 
Poll
Which party will you be voting for in the General Election 2017?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.