# Tag Info

### Applicability of the $\frac{1}{4\pi}$ pre-factor for Coulomb Attraction in Nanocrystals

Solved thanks to Andrew: The value of "1.8" results from the integration of the 1S eigenstates, which is independent on the choice of unit system. It can hence be concluded that option two ...
1 vote
Accepted

### Rutherford scattering closest approach distance

Go through this sequence. Find the velocity of the centre of mass. Find the velocity of the two particles in the Com frame. Find the sum of the kinetic energies of the two particles in the CoM frame. ...
• 96.8k

### How do two things attracted to each other move in mechanics?

How do you describe their motion? However makes the problem easiest. One of the neat things about physics is that you can frame the problem differently, work the math, and come up with the same ...
• 49.7k

### How do two things attracted to each other move in mechanics?

In case of no external forces, just mutual interactions, like gravitation, Coulomb force or spring force that is net same on both, we take the reference frame as center of mass which allows us to ...
Accepted

### Convert Coulomb's law in CGS units to SI units

Coulomb's law gives the force between two charges. This force is proportional to each of the two charges, and inversely proportional to the square of the distance between them. So, we will have some ...
• 2,133

### Does force between two charges depend on medium?

When the two charges are kept in a medium of dielectric constant k then the net force between the charges decreases. But the electrostatic force applied by one charge on the other remains same.

### Can any object pass into the event horizon of a black hole and then escape?

Hawking radiation is not escaping the black hole. Instead, the effect of this apparent "escaping" is due to two random particles appearing, one extremely close to the event horizon of the ...
Accepted

### Electrons repel each other forever - why?

The reason you might feel that electrons should 'lose' their ability affect other electrons might be because the entropy of the universe is increasing which means the amount of 'useless' energy of the ...

### Electrons repel each other forever - why?

There's really not much to explain here. The conservation of electric charge is consistent with every experiment which has ever been performed, and so it is built in to essentially all of our models (...
• 69.9k