# Search results

1. ### Atomic excitation via photon absorption

Right, how about an atom absorbing the excitation energy it needs from an incoming blue photon, and the photon leaves with the remainder of its original energy, except now that it has a lower frequency, say red?
2. ### Atomic excitation via photon absorption

Then does the theory disallow the possibility of absorbing a portion the energy of an of an incoming say, violet photon and and render the photon into say, a green photon whose frequency corresponds to that of the remainder energy
3. ### Internal energy change

Hi Guys! I have a confusion which I hope you can help clear up. The mathematical expression of the first law of thermodynamics can be stated as δu=Q+W where u is the internal energy of the system, Q is the heat added(or taken from) to the system and W is the work done by or on the system. If I...
4. ### Atomic excitation via photon absorption

OK so just to clarify, the quantum theory explains that radiation is carried by discrete packets of energy (photons) whose energy must also be discrete? Would that mean orange light from a sodium lamp cannot be changed in any way into other colours by altering the frequency of the "orange" photons?
5. ### Atomic excitation via photon absorption

Isn't the energy of a photon continuous, since its frequency can take on any value?
6. ### Atomic excitation via photon absorption

What if the frequency of the photon decreases to the corresponding amount of the remainder energy? i.e. the frequency of the photon decreases after some of its energy is absorbed by the atom.
7. ### Atomic excitation via photon absorption

Hi guys! I have come across a problem I can't seem to wrap my head around. I've learned that E.M. radiation can be propagated by discrete packets of energy , photons. Is the energy of each photon discrete, or can it have a continuous range of energies depending on its frequency? I would be...
8. ### Standing Waves

Okay I am starting to see the gist of it, but could you care to explain why harmonics are required for solid boundaries but not for open-ended conditions? Do sound waves in a pipe count as open-ended or bounded?
9. ### Standing Waves

I am a little bit confused though, do standing waves form at all frequencies as long as you have two waves of similar amplitude and frequency traveling in opposite directions? For resonance only then you need harmonics?
10. ### Standing Waves

Also, are standing waves examples of resonance?
11. ### Standing Waves

So to answer my question, standing waves on a string attached to a fixed point do not require harmonics whereas standing waves between two speakers do?
12. ### Standing Waves

For transverse waves on a spring, doesn't the applied frequency have to be one of the harmonics to form standing waves? By boundary conditions, I assume those are the variables in the fundamental frequency formula?
13. ### Standing Waves

If so then standing waves are just resonance in work?
14. ### Standing Waves

Do all frequencies produce standing waves or just the harmonics? My physics textbook stated that standing waves are form when two wave trains with equal amplitude and frequency meet each other in opposite directions. Does the common frequency of the wave trains have to be one of the harmonics...
15. ### Summation of series

Homework Statement Let v1, v2, v3 be a sequence and let un=nvn-(n+1)vn+1 for n= 1,2,3... find \sumun from n=1 to N. Homework Equations The Attempt at a Solution Began with method of differences and arrived at Sn= v1-(n+1)vn+1
16. ### Gravity and upward motion

I am starting to see your point here, but allow me to ask: when the ball leaves the hand, it will still travel upwards, right? Shouldn't the be a upward force compelling it to move?
17. ### Gravity and upward motion

Hello everyone, I am have some confusion regarding gravity and a ball traveling upwards. Suppose you throw a ball upwards into the air. At the beginning, the ball is at rest atop your hand, Freaction=mg. When your hand moves upwards to throw the ball, Freaction>mg and the ball accelerates...
18. ### Sensitivity and Uncertainty in measurements

By rounding to the nearest actual marking, the systematic uncertainty increases from 0.25mm to 0.50mm? Is that what you mean?
19. ### Sensitivity and Uncertainty in measurements

Greetings fellow members, I have some queries on a laughably rudimental topic regarding measurements. Say you have a metre rule with sensitivity of 0.1cm, and you are measuring a wire which stretches from the 0.0cm starting point to the middle point between 7.3 cm and 7.4cm. My...
20. ### Heat released during freezing of water

Alright looks like I was correct. Thanks Borek :)
21. ### Heat released during freezing of water

Well this question is purely qualitative, there are no calculations involved. Since my description of the question wasn't quite clear I shall copy the question itself The diagram below shows a thermometer placed in a beaker of acetone and its reading is τ1. When the thermometer is taken out...
22. ### Heat released during freezing of water

Homework Statement A situation is given whereby a thermometer is placed inside acetone of 80C and is taken out. A layer of ice forms around the surface of the thermometer, does the reading of the thermometer change? Homework Equations - The Attempt at a Solution At first I...
23. ### Calculate the temperature of a mixture

My attempt resulted in a negative answer, which confuses me as it is quite impossible.Then the second question asked for the mass of ice remaining which made me realize that not all of the ice has melted
24. ### Calculate the temperature of a mixture

Homework Statement Calculate the temperature of a mixture of 0.3kg ice at 0°C and 0.3kg water at 75°C.Find the mass of ice melted Homework Equations Specific heat capacity of water: 4200J/kg/°C Specific latent heat of fusion of ice: 334 000 J/ kg The Attempt at a Solution Got a negative...