4:17 AM
3

My teacher says that a rest charge creates an electric field and a moving charge creates both electric and magnetic fields. But, the cause of a magnetic field is velocity, so, is there something which changes an electric field into a magnetic field? Question: Can an electric field be converted in...

5:08 AM
6

If I shine a light on a concave mirror, all of the rays will be reflected through its focal point. What happens if I heat it? Is heat going to be radiated through the focal point or will it be spread in all directions? Edit: The question is about direction of heat emissions. Is heat emitted in on...

12 hours later…
5:29 PM
2

Mean kinetic energy is related to temperature: $$\langle K_E\rangle=\frac{3}{2}kT=\frac{1}{2}mv^2$$ where $k$ is the Boltzmann constant and $T$ the temperature in Kelvin. For example, the average molar mass of air is 29 g/mol, the average $K_E$ of air molecules at 20°C (293K) is approximately \$6\...

5:55 PM
2

A discussion question in my book is: "Why is it difficult for a fireman to hold a hose, which ejects large amounts of water at a high velocity." Its answer is given as: When a fireman holds a hose, which is ejecting large amounts of water at a high velocity, then a reaction force is exerted on...