## ketz 4 years ago Use Coulomb’s Law to determine the magnitude and direction of the electric field EB at point B in the diagram due to the two positive charges (Q = 7.0 μC). If a proton is located at point B, calculate the magnitude and direction of the force F acting on the proton.

1. ketz

2. ketz

Urgent answer needed!! (I've exams tomorrow)

3. anonymous

Do you understand vector notation?

4. anonymous

it shows the direction of vector quantity...

5. ketz

6. NoelGreco

$E=k \frac{ Q }{ r ^{2} }$ Calculate the magnitude of the electric field at point B

7. anonymous

|dw:1348614053138:dw|

8. anonymous

E1 has the same direction as r1 E2 has the same direction as r2 find the magnitudes of each field in terms of Q find the 'x' and 'y' components of each field add the 'y' components; add the x components : those sums are the components of the net field

9. anonymous

10. anonymous

@Algebraic! PLEASE MAKE IT MORE CLEARER

11. anonymous

what part?

12. anonymous

finding magnitudes of E?

13. anonymous

E1: (9E9*7E-6)/.005m etc

14. anonymous

YEA..I WAS THINK THE 2 CHARGES WILL ADD UP ALGEBRAICALLY AND THE RESULTANT WILL HAVE EFFECT ON THE TEST CHARGE PROTON

15. anonymous

direction of E1 : angle is 45 so E1x = ((9E9*7E-6)/.005m) *cos(45) E1y =((9E9*7E-6)/.005m) *sin(45) (edited: now with more parentheses!!_

16. anonymous

PLS HOW DID THE ANGLE BECOME 45 DEGREES

17. anonymous

well...

18. anonymous

|dw:1348615004630:dw|

19. anonymous

that's better

20. anonymous

does that clear it up?

21. anonymous

yep it does

22. anonymous

so you got E2 (mag. and direction/components) ?

23. anonymous

@Algebraic! yep its clear on how to get E2 but the question also want the force F acting on the proton also after getting the x and y components of E1 and E 2 how will it be added

24. anonymous

yeah once you find the net field at a point, the force on a particle at that point is just qE, where q is the charge of the particle (the charge of a proton in this case: +e) "also after getting the x and y components of E1 and E 2 how will it be added" just add them! add the x comp of E1 and the x comp of E2, that's the x comp of the net field... repeat for y comp to find the magnitude of the net field, use sqrt( (x comp)^2 + (y comp)^2 ) to find the direction of the net field, use arctan( x comp / y comp)

25. anonymous

i really learnt alot from you @Algebraic!

26. anonymous

haha! good! I hope so!