The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

Specific charge

What is the specific charge of Magnesium ion? (Mg2+)

For what I did is : Specific charge = charge / mass
= (2x1.6x10-19)/(24x1.67x10-27+10x9.11x10-31)
= 8330000
= 8.33 x 106 C/kg
However the answer from the book is 7.98 x 106 C/kg. What have I done wrong?
Reply 1
Avatar for xboc
xboc
12
Original post by alesha98
What is the specific charge of Magnesium ion? (Mg2+)

For what I did is : Specific charge = charge / mass
= (2x1.6x10-19)/(24x1.67x10-27+10x9.11x10-31)
= 8330000
= 8.33 x 106 C/kg
However the answer from the book is 7.98 x 106 C/kg. What have I done wrong?


Calculate again, i got the correct answer
Reply 2
Avatar for alesha98
alesha98
OP
4
Original post by lyamlim97
Calculate again, i got the correct answer


Ok, i tried again , using the formula I have posted, and still got the same answer. (8331356.806)
Reply 3
Avatar for xboc
xboc
12
Original post by alesha98
Ok, i tried again , using the formula I have posted, and still got the same answer. (8331356.806)


I used what u wrote and i got the correct answers. Check your brackets when using a calculator
Original post by lyamlim97
I used what u wrote and i got the correct answers. Check your brackets when using a calculator


^^
make sure your standard form is correct as well
Reply 5
Avatar for alesha98
alesha98
OP
4
Original post by CheeseIsVeg
^^
make sure your standard form is correct as well


What is the formula you used and what answer u got?
Original post by alesha98
What is the formula you used and what answer u got?


used your formula but i added a bracket here:
(2x1.6x10-19)/((24x1.67x10-27)+(10x9.11x10-31))
Reply 7
Avatar for alesha98
alesha98
OP
4
Original post by CheeseIsVeg
used your formula but i added a bracket here:
(2x1.6x10-19)/((24x1.67x10-27)+(10x9.11x10-31))


and what did you get?
Reply 8
Avatar for alesha98
alesha98
OP
4
Original post by alesha98
and what did you get?


Multiply before addition, so bracket should not be a problem there.
Original post by alesha98
and what did you get?


I got the textbook answer
Insert brackets there and you should get the right answer
Just try it, honestly :wink:
Reply 10
Avatar for alesha98
alesha98
OP
4
Original post by CheeseIsVeg
I got the textbook answer
Insert brackets there and you should get the right answer
Just try it, honestly :wink:


Why do I need to add bracket there?
Original post by alesha98
Why do I need to add bracket there?


otherwise you get the wrong answer?!?!
JUST TRY IT!
Reply 12
Avatar for alesha98
alesha98
OP
4
Original post by CheeseIsVeg
otherwise you get the wrong answer?!?!
JUST TRY IT!


I try but I will not include the bracket if i don't understand the reason.
Original post by alesha98
I try but I will not include the bracket if i don't understand the reason.


wuuuuuuuuuuuuuuuuuuuuuuuuuuuuuut
its so the calculator understands
Reply 14
Avatar for xboc
xboc
12
Original post by alesha98
Multiply before addition, so bracket should not be a problem there.


To us humans, we know that and apply it automatically. However to a computer or calculator in this case, it might or might not be programmed to recognize that. Hence in your case, it has proven not to so you have to include brackets for the calculator to understand.

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you