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1d
answered Would adding water after heating decrease the overall heat, when compared to adding the water before heating for the same period of time?
Oct
20
answered What does it mean by $t=-1$?
Oct
20
comment What is the relative speed of the galaxy with respect to the Earth
The wavelength values give you a Doppler shift. Look up the equation between Doppler shift and $\frac vc$
Oct
20
answered How to find how far away could a binary system be?
Oct
14
answered Correcting for oblateness of the Earth
Oct
9
comment Voltage and resistors
No, electrons have a potential energy based on the voltage level they are at. That is what changes on the passage through the resistor. It is like a rock rolling down a hill. When it is high on the hill it has a lot of potential energy. After it stops rolling at the bottom, it has the same kinetic energy (zero) as it had before it started rolling, but less potential energy. Electrons in a potential field work the same way.
Oct
8
comment Voltage and resistors
As I said, the same number enter as leave. They just leave with less energy than they entered at. This energy difference is the heat dissipated by the resistor.
Oct
8
answered Voltage and resistors
Oct
8
answered Does turning a light off save electricity in a room heated by an electric space heater?
Oct
6
comment What is the electric field near an infinite sheet with a point charge near by?
Is the sheet conductive or insulating. For conductive, you need to consider an image charge. For insulating, you can just use superposition.
Oct
5
comment If mass is added to a toy car does it affect its speed making it faster
No, generally it will fall slower. It has less drag, but with a lower mass the drag causes more deceleration. If they are spheres, the drag goes up as $r^2$ (the cross sectional area) while the mass goes up as $r^3$ (the volume)
Oct
5
comment If mass is added to a toy car does it affect its speed making it faster
OP explicitly wants to consider drag.
Oct
5
comment How many are the points which are $n$th nearest to a certain point in a hexagonal lattice
For questions like this, you should count the numbers for small distances, then look in oeis.org. There are three at a distance of one, six at distance $\sqrt 3$, three at distance $2$, six at the next. A search for $3,6,3,6$ gives 21 pages, not too many to look over.
Oct
5
answered Time Dilation, Multiple Earth's?
Oct
4
answered Effect of steering a car at high speed
Sep
30
comment Is a given charge density a surface charge density or volume charge density?
If you don't, consider a cylinder that crosses the surface, large in diameter compared to the height. There is no E field through the sides of the cylinder, only through the circular faces. Use Gauss' law to find the difference in E field between the two circles.
Sep
30
comment Is a given charge density a surface charge density or volume charge density?
You have the E field between the conductors given in the problem by taking the derivative of the potential. You know the E field is zero inside the conductors. This gives you a step change as you cross the surface of the conductor, caused by the surface charge. That is where I say you should have an equation for the step change in E field caused by a surface charge.
Sep
29
comment Is a given charge density a surface charge density or volume charge density?
There is no volume charge density in conductors, because it would set up an electric field in the conductor, which it cannot support. If you have an insulator, you might have (and would expect it to be) a volume distribution.
Sep
29
answered Is a given charge density a surface charge density or volume charge density?
Sep
28
answered Does the photoelectric effect require a battery or a circuit?