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# Specific charge Watch

1. 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?
2. (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
3. (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)
4. (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
5. (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
6. (Original post by CheeseIsVeg)
^^
make sure your standard form is correct as well
What is the formula you used and what answer u got?
7. (Original post by alesha98)
What is the formula you used and what answer u got?
(2x1.6x10-19)/((24x1.67x10-27)+(10x9.11x10-31))
8. (Original post by CheeseIsVeg)
(2x1.6x10-19)/((24x1.67x10-27)+(10x9.11x10-31))
and what did you get?
9. (Original post by alesha98)
and what did you get?
Multiply before addition, so bracket should not be a problem there.
10. (Original post by alesha98)
and what did you get?
Insert brackets there and you should get the right answer
Just try it, honestly
11. (Original post by CheeseIsVeg)
Insert brackets there and you should get the right answer
Just try it, honestly
Why do I need to add bracket there?
12. (Original post by alesha98)
Why do I need to add bracket there?
otherwise you get the wrong answer?!?!
JUST TRY IT!
13. (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.
14. (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
15. (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.

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