Light Definition and 1000 Threads

1) really does not make sense to me. It is not clear to me how light could be reflected in multiple directions if the source is not a tilted mirror or another object with specific properties. I think the thought of the "point" P confuses me. Further, the fact that light travels in the opposite...

Is there a way to create a map from satellites showing how much light pollution there is on earth? For example if you wanted to do astro photography and wanted to know how far away from city you need to drive to see certain levels of detail from galaxy?

Hello, I'm trying to focus a 275nm (with proper safety precautions) LED that looks to be a few mm in length and width (the light-emitting portion) to a smaller dot size. The LED should probably be fairly close to the surface of the lens to collect more of the light. The dot size would hopefully...

Sketch

I have been given the task of modeling the heat transfer from a light source of known power into a system consisting of two connected materials. I must find the temperature change in the bottom surface. The two materials are initially in thermal equilibrium with the surroundings. My first...

My Next DIY, So, I'm guessing something like this may already exists (see image) light bulbs added for clarification purposes only. Anyone know if there's something like this already on the market? So, I did a google search for custom toggle switches but most if not all were for Marine or...

Does Ohm’s Law, V = IR work for light bulbs? It appears not to from my simple experiment below. In the figure below, I measured the resistance of a lightbulb and found that resistance to be 2.6 ohms. However, when I connect this lightbulb into the circuit where I measure the voltage across...

We can measure the two-way speed of light, but not, apparently, the one-way speed. Light could travel at c in every direction or c/2 in one direction and instantaneously in the other. Nature does not provide us with a way of determining the one-way speed. I can follow some of the basic...

I get it, it sounds cool. But it is a very misleading and sometimes confusing way to represent c. The speed of light is not constant. When I say that, I’m talking about the speed of LIGHT. Not c. Cherenkov radiation is a result of particles moving through some material (usually water) faster...

I watched a fermilab video claiming objects don't actually gain mass as they approach light speed. Is that true? What keeps things of mass from reaching the speed of light or beyond? I assume matter doesn't accumulate higgs-bosons while in motion?

A ship that moves at a speed very close to light, its relative mass increases and may be comparable to the mass of the planets or the sun, in this case it can change the orbit of the planets and the sun (according to the law of gravity of two bodies) Is this analysis correct?

The experimentally measured properties of protons and neutrons are known with exquisite detail. Our data is not quite as extremely precise, but still very good more other baryons and mesons with light quarks (u, d, and s) as valence quarks, such as pions and kaons. Yet, on a percentage basis...

hello everyone! Recently,i'm reading a paper about slow light,that's really a famous work published in Nature.[Light speed reduction to 17 metrespersecond in an ultracold atomicgas]. But I'm trouble with some calculation about the velocity of slow light.here are below: i try to use the...

Is it possible to store large quantities of light for extended periods of time? If so would it make any sense to use it to propel a spaceship because it doesn't weigh anything? I read that one of the biggest issues with getting to space is the weight of the fuel.

I am taking a summer course on special relativity and I stumbled across this problem and solution which I tought look neat. However, I think the solution provided for a) there is wrong. I will here present two of my solutions for a) and one solution for b) and ask if you think mine are okay? :)...

Phase difference is $\phi=\frac{2pi}{\lambda}* \Delta+\pi$ Phase difference, max: $\Delta \phi=2pim=\frac{2pi}{\lamda_{max}}*2nd$ Phase difference, max: $\Delta \phi=2pim=\frac{2pi}{\lamda_{min}}*2nd+pi$ Flim thickness: $d=100nm$ Set the equations equal to each other i got a d=-100nm which...

Hello, I am looking for something a bit out of my wheelhouse today, gamma light sources (10 MeV or higher on the max energy threshold). Does anyone here have experience or more information on these machines? Are they typically electron accelerators utilizing a tungsten or tantalum target? I am...

In special relativity I can get ## \gamma ## , ## \frac {T_B}{T_A}=\gamma ## Why do I not go ##{T_B} - {T_A} = \gamma## ? ##T_B = \frac {2H} {c^2 - v^2}## . ## T_B ## is the moving light clock. ## T_A = \frac {2H} {c^2} ## . ##T_A ## is the stationary light clockI assume LaTeX doesn't work...

My book says: I don't understand why the bottom eye only sees the horizontal red arrow and not the other angles (black arrows)

I found that I had an inaccurate understanding of their relationship earlier. After rethinking, I try to express their relationship in a simple and understandable way Nuclear reactions convert energy from form of mass to form of light, and both energy and momentum are conserved during the...

https://www.linkedin.com/in/hellandhansen/ CMO at an ophthalmological tech company; Bulbitech. Now initiated an industrial PhD at the University of Oslo, supported by a Norwegian Research Council grant, where I will work on one of our tests (retinal adaptation speed to different lighting...

In doing a project on phototransistors I am using my smartphone as illumination source. In order to find the responsivity of the induced current from the light, I need to know the surface power density, which I could estimate, if I knew the effective optical power of the light from the...

I'm quite aware that according to Einstein light is a particle and a wave at the same time. However, I try to imagine how exactly would light expand. A photon must likely have a certain timing for expansion. I mean, after a photon is originated it immedialy multiplies itself into many other...

i think that the light sphere will go up higher(will have bigger acceleration) because there has to be a balance between the mass and the acceleration as long as the force is the same, for example if you push a heavy object and with the same force pushed another light object the light object...

Hello, Is there a mirror that will reflect light in parallel trajectories ? If yes, is the reflected light in sync, and will all beams hit a flat surface simultaneously ? Thank you

Intuitively, the Rindler wedge is timelike in Minkowski coordinates and an object crossing the horizon enters a spacelike region. This seems at odds with my understanding of the light cone where the 2 regions are reversed. I think this may be related to the signature of the metric but I'm not...

More or less all ICF schemes seem to be similar to the first artificial fusion method (also inertial) of the secondary of the hydrogen bomb. Before I present the question let me show just another ICF approach recently done. The company is called "first light fusion", Their method is essentially...

I am 74yo and love Physics. If my basic knowledge of physics is correct, light is a photon. My question is: 1. Is the reason we cannot see infrared light because the spectrum travels at a wave link our eyes cannot see? 2. Does the light from the sun have all the different waves combined, and we...

The question constantly arises how the speed of light is measured and what does it mean that the speed is constant, including at remote points for the observer, including at points beyond the local frame of reference, as you understand it in general relativity (GR). First of all, it should be...

I realize turn into probably isn't the correct term. Also I know gravity can bend light but can gravity cause light to turn into other particles? I am layman so can someone explain this in layman's term? Also I am not even sure the quantum section is the correct section.

(edit.. not the red light, that's my emergency power outage light in every frame, I'm referring to 3:57am and exactly 15 seconds, blink and you will miss it) turn up the volume Strange white/yellow flash appeared in my room and the sound it made when the light hit my security camera sounded...

Homework Statement:: Einsteins Theorie Relevant Equations:: Theorie Hi. My name is Sven Dahlhaus. I'm from Germany and just got my high school diploma. Nevertheless, I am a big fan of theoretical physics. There is a question that bothers me a lot. According to Einstein's theory, nothing can...

I know that red light has a lower index of refraction than blue light, but that’s not what I’m seeing. The blue light is where the red light should be. I can’t afford to join CHEGG. Any chance that someone would help me out for free? I’d really appreciate it. [Link to chegg removed by the Mentors]

The idea is to have 2 clocks at position A and B. The clocks are synchronized by sending a light pulse from position S over 2 equal distances x. The receiver is at position R at a distance y rectangular to the direction AB and exactly in the middle between A and B and right below S. for proofing...

ρ_kdk = k^2/π^2 dk is the density of field modes (what we are trying to solve for here), and as ρ_kdk = ρ_λdλ, and k=2π/λ, we can rearrange this to get ρ_λdλ = 8π/λ^4dλ This is where my confusion lies. I am not sure what to do next. I know this equation physically means the number of modes per...

Could I please ask for help in how to do this question. Is it in fact well formed, can it be solved as it is or do I need more information? Q. Find the external forces and the force in each rod in the following framework of light rods which is supported and A and C: So, I need to find Fa...

Been thinking about this since I was 12. Suppose you had a 1 lightyear long pole, and on the other end was a button 1 inch away that activates a light. The light is powerful enough for you to see it 1 lightyear away. You push the pole 1 inch forward. How long does it take for the light to reach...

Please bear with me I am trying to get a grip with underlying principles. Starting to try and understand Einstein’s second postulate and distinguish that the speed of light is independent of the speed of the source – v - of objects, other than light with travel initiated independent of the...

Can I understand that light energy contains heat energy? or Do I have to separate between two concepts? because light energy from the sun makes heat energy after absorption of molecular?

if someone want to explain to me what is an upright image ? , and what are the other adjectives to define an image in geometric optics and their meaning , Thanks .

If you're in a relativistic starship, approaching the speed of light, then if you get too close to it, do you end up becoming a black hole? Relativistic length decreases as you get closer to light speed. Relativistic mass increases as you do the same. Will your relativistic mass and relativistic...

Hi everyone! Hope your day is going well. I’m an ex-physics student who recently wanted to go back to studying the subject (as a hobby, mostly). So I picked up Zee’s GR book since GR is the thing I’m the most interested in. I expected to hit a wall on some basic things since I’m rusty, and did...

Hello, I built myself a spectroscope with a CD (where I removed the coating), similar to this one: With this I now want to look at light sources. However, some interesting lamps are a bit too bright to comfortably look directly into (through the spectroscope). Does anyone have an idea how to...

I know that in order for the two lights to be distinguishable from one another they have to be separated by an angle of at least theta = 1.22(wavelength)/(width of aperture). I tried drawing the given picture below and then using trig to find L in terms of d/2 and theta/2. However, this ended up...

One of the reasons to suggest that light might be bent by gravity is the assumption that light is behaving as the other objects that bend their trajectories by gravity. On a similar ground, we could suggest that as the objects are experiencing Gravity Assist, then the light could be also...

As we all know, light itself is the fastest thing in the universe, and the cosmic speed limit, basically. That said, it is said to go at 299,792,458 meters per second in a vacuum. That is pretty fast. However, I have a question I want to ask... Does light really go that fast in a vacuum? I ask...

Source: https://bigthink.com/starts-with-a-bang/fast-space-expanding/ I need help with the part in red. What does it mean when it says light is redshifted by 70 km/s? When the redshift occurs the wavelength increases which is measured in meters or kilometers. I don't understand the "per second"...

I understand the relativistic effects at high speeds, what accounts for the constant speed of light at low speeds? Example... If I travel towards a beam of light at 25 MPH, I will still measure the light as traveling towards me at the speed of light and not the speed of light plus 25 MPH.

Case 1 worked out great, I found it to be linearly polarized light at an angle ##\alpha = \frac{\pi}{4}##, but Case 2 is giving me trouble. As best I can tell, ##\alpha## is undefined in case 2. How do I solve case 2?

Good evening all, I had a question on how the standard for the meter is defined. A simple Google search tells us that since 1983, the meter has been internationally defined as the length of the path traveled by light in vacuum during a time interval of 1 / 299, 792, 458 of a second. Many other...