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posted by  frasifrasi on 9/13/2008 10:28:30 AM  |  status: Live  

Help me with this electric field question : ) - Thanks (will rate and be grateful)

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General Physics N/A N/A N/A
Question Details:
the question is:
Two particles with positive charges q_1 and q_2 are separated by a distance s.
 
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Along the line connecting the two charges, at what distance from the charge q_1 is the total electric field from the two charges zero?
Express your answer in terms of some or all of the variables s, q_1, q_2 and k =
.
 
Thank you so very much everyone - I am stuck.
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Oracle
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posted by Antony08 on 9/13/2008 11:02:36 AM  |  status: Live
Asker's Rating: Lifesaver   
frasifrasi's comment:
"thank you very much"
Response Details:
Let at a distance x from charge q1 the electric field is zero.
Therefore,the electric field due to charge q1 at distance x is
E1 = (1/4πεo) * (q1/x2)
 
The electric field due to charge q2 at distance (s + x) is
E2 = (1/4πεo) * (q1/(s + x)2)
 
When the total electric field due to the two charges is zero,then
E1 + E2 = (1/4πεo) * [(q1/x2) + (q2/(s + x)2)] = 0
or x = -[(s)/(1 + (q2/q1)1/2)]
The negative value of distance indicates that the charge should be placed in a direction opposite to the direction we have considered.
Oracle
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posted by booboo123 on 9/13/2008 11:06:32 AM  |  status: Live
Asker's Rating: Helpful   
frasifrasi's comment:
"appreciated"
Response Details:
let's assume at distance x from q1 the field will be zero, will can express both fields as follows:
 
 
note that one is negative and one is positive since they are in different direction.
 
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