A2 Electric Field Strength - Help! Watch

crc290
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Question is in the spoiler. I honestly have no idea how to do it

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A +25μC point charge Q1 is at a distance of 60mm from a +100μC charge Q2.

a) A +15pC charge q is placed at M, 25mm from Q1 and 35mm from Q2. Calculate: i) the resultant electric field strength at M, ii) the magnitude and direction of the force on q.

b) Show that the electric field strength due to Q1 and Q2 is zero at the point which is 20mm from Q1 and 40mm from Q2.


Any advice would be helpful
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M1K3
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Do you know the formula? E = (1/(4.pi.epsilon))(q/r^2)

E being the electric field strength.

So determine the field strength due to each of the point charges using this formula yeah? That should start you off. Then you know that the defining equation for the electric field is E = F/q so u can deduce the force from there.
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crc290
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(Original post by M1K3)
Do you know the formula? E = (1/(4.pi.epsilon))(q/r^2)

E being the electric field strength.

So determine the field strength due to each of the point charges using this formula yeah? That should start you off. Then you know that the defining equation for the electric field is E = F/q so u can deduce the force from there.

Thanks for your help

Yes I know the formula. I did actually try using it to begin with but I wasn't sure if the charge at point M is taken into account or not :confused:

EDIT: Oh wait, never mind. I understand it now. Thanks again
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M1K3
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(Original post by crc290)
Thanks for your help

Yes I know the formula. I did actually try using it to begin with but I wasn't sure if the charge at point M is taken into account or not :confused:

EDIT: Oh wait, never mind. I understand it now. Thanks again
np
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danthedude
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Resultant electric field strength = E_1 - E_2
where E_1 is larger and E=\frac{Q}{4\pi{\epsilon_0}r^2}
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GrimsAgent
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Hi,
I'm also stuck on this question.
I understand the equation but I don't know what the +15pC is?
Is it meant to be 15*1.6*10^-16 (as in the charge of a proton?)
Thanks
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Stonebridge
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(Original post by GrimsAgent)
Hi,
I'm also stuck on this question.
I understand the equation but I don't know what the +15pC is?
Is it meant to be 15*1.6*10^-16 (as in the charge of a proton?)
Thanks
No it's 15 pico coulombs
pico is 10-12
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