R - Galileo and Einstein
R - Galileo and Einstein
R - Galileo and Einstein
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Field from Two Equal Charges<br />
• Two charges Q are placed on the y-axis, equal distances d<br />
from the origin up <strong>and</strong> down. What is the electric field at a<br />
point P on the x-axis, <strong>and</strong> where is its maximum value?<br />
y-axis<br />
x-axis<br />
Q<br />
d<br />
d<br />
Q<br />
x<br />
r<br />
<br />
P<br />
<br />
E<br />
E total<br />
<br />
kQrˆ<br />
r<br />
upper charge 2<br />
• Anywhere on the axis, the field is along the axis, <strong>and</strong> has value<br />
E<br />
2 2 2<br />
kQ cos kQx <br />
kQx .<br />
r 2 r 3 2 2<br />
x d<br />
3/2
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