Linked Questions
10 questions linked to/from Why does this line integral give the wrong sign?
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Sign of the integral for the work done to bring two charges together (Purcell and Morin E&M 3rd ed, page 12) [duplicate]
My concrete problem is, the final sign on the integral.
Purcell and Morin, Electricity and Magnetism third (3rd) edition on page 12. They show a simple calculation of the work required to bring two ...
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Gravitational potential at any point [duplicate]
What's wrong in this derivation of potential at any point? Its showing GPE at any point is +ve but its supposed to be negative right?
Supoose a object is being moved from infinity to a point at ...
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Why is the derivation of gravitational potential energy incorrect if we consider bringing a mass from infinity to a distance $r$ from another mass? [duplicate]
The gravitational potential energy of a mass at a point in a field is defined as the work done by an external agent in bringing that mass from infinity to that point, without a change in kinetic ...
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Why am I getting Work done as negative in bringing a positive charge near another positive charge? [duplicate]
Let us consider a charge $Q>0$ at origin. Let $P(r,0)$ where $r>0$ be on $X$ axis.Consider a point $M(x,0),\:x>r$ from which we have to move a charge $q>0$ towards point $P$.
Now I am the ...
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Why the work done is positive when bringing 2 opposite charges together?
We know that if the applied force is in the direction of the displacement then work done is positive, but in case of bringing 2 opposite charges from infinite to a certain distance, the work done is ...
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Reason for adding the negative sign in the expression of electrostatic potential energy for the differential element of distance
My physics professor taught us that whenever we express the electrostatic potential energy, we usually write the expression as,
$$\displaystyle\int_\infty^0\dfrac{Q}{4\pi\epsilon_0r^2}\,(-dr)\cos0.$$
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Conservation of Energy For Electrostatics
Starting from Newton's second law, I am trying to show that energy is not conserved with an applied external force when moving a positive charge from $r_b$ to $r_a$ (see image). I'm not sure where I'm ...
user330929
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How to choose the sign of the differential?
I know this is a very simple question, and I have searched it too. How to avoid incorrect symbols in calculation results.I don’t understand how to choose the sign of $ds$.
An object moves from a to b,...
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Integrating cross products
I know that while integrating dot product to two vector quantities along a line integral, the limits of the integration implicitly takes care of the direction in which we integrate from here and here.
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There is something I don't understand in the answer of the following question [duplicate]
Q. The gravitational field due to a mass distribution is given by $E=k/(x^3)$ in $x$-direction. Taking the
gravitational potential to be zero at infinity, find its value at a distance $x$.
for the ...
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