What is Shift: Definition and 653 Discussions

Shift work is an employment practice designed to make use of, or provide service across, all 24 hours of the clock each day of the week (often abbreviated as 24/7). The practice typically sees the day divided into shifts, set periods of time during which different groups of workers perform their duties. The term "shift work" includes both long-term night shifts and work schedules in which employees change or rotate shifts.In medicine and epidemiology, shift work is considered a risk factor for some health problems in some individuals, as disruption to circadian rhythms may increase the probability of developing cardiovascular disease, cognitive impairment, diabetes, and obesity, among other conditions.

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  1. N

    Reflection of a plane mirror and phase shift

    Homework Statement Hi I think I have confused myself: If I have a linearly polarized beam incident on a plane mirror with higher index, will the 180-degree phase shift change the direction of the polarization? Say, from lying in the 1st-3rd quadrant to lying in the 2nd-4th quadrant...
  2. K

    The meaning of z number in red shift

    Hello I understand that red shift is a measurement of relative speed. What I am looking for is what the number after the z means. Is it a percent of c or, Or is it it just a scale that physics uses to note the difference between different objects. Thanks for your time. Kevin
  3. G

    Why does Raman shift increase as temperature decreases?

    This was a quick short answer question from a previous final exam I'm studying from - the prof didn't provide an answer key. I can't think of any physical reason why this should happen. I can explain why the stokes/anti-stokes intensities vary with temperature, and why the linewidths vary...
  4. S

    Doppler shift of an approaching source with interference problem

    Homework Statement P15. The police car with its 300 Hz siren is moving toward a warehouse at 30 m/s, intending to crash through the door. What frequency does the driver of the police car hear reflected from the warehouse? (5 marks) Homework Equations doppler shift for an approaching...
  5. C

    Use doppler shift to find star velocity

    Homework Statement How fast would a star have to travel to make violet light (λ = 400 nm) appear to be blue (λ = 450 nm)? Assume the star is moving along the line that connects the star to the Earth. Homework Equations λr = λc / (c-Vr) f= fo (c +- Vr / c +- Vs) The Attempt at a...
  6. C

    Estimating Doppler Shift for a Radio Wave

    Homework Statement Estimate the Doppler shift for a radio wave reflected from an airplane moving directly toward you at a speed of 292 m/s. Assume the radio wave has a frequency of 9.7x10^6 Hz. Homework Equations fo = fv/(v − vt) The Attempt at a Solution Using the above...
  7. T

    Four-Momentum of Photon / Doppler shift in General Relativity

    Hi, I'm trying to understand a derivation / question for my revision. It has to do with the four momentum of a photon and doppler/redshifts. Homework Statement Show that ratio between emitted and received frequencies (for two observers E and R moving with velocities u and v respectively)...
  8. S

    Help With 180 Degree Phase Shift

    I want to take an audio signal, and shift the waveform 180 degrees. How would I do this? I have read that if you take a simple class a amplifier, and feed the signal into the base of the NPN transistor, you will get an output that is shifted 180 degress. Example: Will this work?
  9. V

    Astronomical spectroscopy and doppler shift.

    Hi! I have two (stupid) questions: 1) We can determine what elements are present in distant stars by studying their spectrum, right? But if the spectrum of some star is redshifted, wouldn't we be fooled into believing some elements to be present there that might not really be there, due to...
  10. N

    How does LC phase shift oscillator work?

    Heya Everyone :blushing: Im slightly confused as to how LC phase shift oscillator work ? Its a circuit consisting of 1 op-amp ( used as oscillator), 1 LC loop, few resistors. The op-amp has a reference voltage applied to the non-inverting end (+ve). The inverting end has a feedback...
  11. T

    Goos hänchen shift and phase shift

    Dear All, I am confusing total internal reflection for a light wave traveling from denser medium to lower dense medium. I know we get lateral shift i.e. goos hänchen shift with total internal reflection, but Do we have phase shift due to goos hänchen shift with total internal reflection...
  12. A

    Find difference in echo times, doppler shift?

    Homework Statement A bat is pursuing an insect, and using echolocation of 41 kHz sound waves to track the insect. The insect is initially 34 cm from the bat but then moves to a distance of 44 cm as it tries to escape. What is the difference in the two echo times that the bat measures...
  13. Z

    Phase shift of reflected light wave

    When a light wave move from a medium with lower refractive index to medium of higher refractive index, at the boundary, the reflected light wave will undergo a phase shift of ∏ rad. Compared to the transmitted light, the reflected light lead by ∏ rad or lag by ∏ rad?
  14. T

    Finding Speed using Doppler Shift

    Homework Statement Light with a frequency of 6.1(1014) Hz is measured from a star known to produce light with a frequency of 6.0(1014). How fast is the star moving toward or away from earth? Homework Equations f = f0(v + vo)/(v-vs. f=observed frequency f0 = original frequency v=wave speed vo =...
  15. T

    Engineering Phase shift in LC tank circuit

    In a lab session we were investigating the LC tank circuit of a superhet radio. The tank consisted of a ferrite coil antenna connected in parallel with a variable capacitor. A signal generator was connected to a second ferrite antenna (the drive antenna) and placed close to the first in order to...
  16. K

    H20 Molecular shift - what is the initial state just below the Dew Point

    Hi all Another question (sorry) Water vapour in the air will phase shift back to liquid when it reaches its Dew Point temp (Partial Pressure = the Saturated Vapour Pressure), OK I have this. For this phase shift I assume that there are Condensation Nuclei and these nuclei are at a lower...
  17. M

    Red/blue shift in classic train/platfom thought experiment?

    To avoid confusion, I'm talking about: "A flash of light is given off at the center of the traincar just as the two observers pass each other. The observer onboard the train sees the front and back of the traincar at fixed distances from the source of light and as such, according to this...
  18. S

    Insert new element to array and how shift char type

    Homework Statement struct student { char name[20]; int id; float gpa; }; student a[20]; Homework Equations insert another element into the array a. The Attempt at a Solution #include<iostream> using namespace std; #include <stdio.h> #include <string.h>...
  19. B

    Proof of Red Shift that indicates Expansion

    What experimental evidence or optical measurements are used to prove that red shift is due to gravitational fields of suns, and is not simply an artefact of light passing through and being diffracted by the matter in the heliosphere of many suns before reaching earth?
  20. K

    Molecular phase shift in a non-enclosed area – how ?

    Hi I have read this and to put it mildly I am confused, so maybe someone can clear this up. The dew point is defined as the point/temperature at which the Partial Pressure of the water vapour within the air packet equals the Saturated Vapour Pressure. I understand that the dew point is a...
  21. M

    Some exercises on relativistic doppler shift?

    My physics teacher has informed us that for our mock waves exam we are going to be given some relativistic questions on doppler shift, as an experiment by our loving masters. We derived the Lorentz factor and some shift equations, but we haven't done anything else and I'd really like some...
  22. F

    Understanding Red Shift: A Derivation from Classical and Relativistic Physics

    This is another one of those concepts where I understand what happens at the macroscopic level, but don't understand the why, or rather what is happening at the fundamental level. Now my understanding of QM has improved a fair amount in the last week thanks to some help from ZapperZ, but I'm...
  23. E

    Doppler shift and Popular Inversion question

    Hi, I've got a multiple choice piece of work to do with some questions I cannot figure out. They are: In regards to red shift, which one is Doppler shift defined as: 1. The increase in wavelength due to Doppler shift, of spectral lines from SPONTANEOUS photon emission from elements on cosmic...
  24. R

    Spectral weight function and the mass shift of a scalar field

    In the Kallen-Lehmann spectral representation (http://en.wikipedia.org/wiki/K%C3%A4ll%C3%A9n%E2%80%93Lehmann_spectral_representation) the interacting propagator is given as a weighted sum over free propagators. The pole of the integracting propagator is, of course, given by p^2=m^2, m being the...
  25. M

    How to shift a focal point af an objective

    Hi, i have a simple optical system composed of: 1. objective with 50 mm focal lenght 2. CCD camera that can not be mounted behind the objective, for mechanical reasons... it can only be mounted 1-2 cm far behind the objective. So i need to "translate" the focal point of the objective 1-2 cm...
  26. S

    Red shift and observable light

    Since light emitted farther away from our point in the universe is more and more red shifted, would this mean that at a certain time we wouldn't be able to observe light further than a fixed distance since it's been red shifted beyond the electromagnetic spectrum?
  27. D

    Conservation of energy in gravitational red shift

    When an em-wave red shifts due to leaving a gravitational field it loses energy, right? Where does that energy go, into gravitational potential energy of the photon? If so does this mean that the photon can "fall" back on the gravitating body to reclaim this energy? What happens to the energy if...
  28. G

    Phase Shift Oscillator Question

    Hello everyone. I understand that a phase shift oscillator works by connecting an amplifier through a feedback network that shifts the input by 180 degrees. Although I remembered building a phase shift oscillator in my circuits class using an omp amp, I would like to build one using a bjt...
  29. J

    A Problem with (Almost) Universal Red Shift

    It is my understanding that, except for a couple of local galaxies, everything in the universe is moving away from us as well as from each other (relationships between inhabitants of local galactic groups excepted). If my information is acurate, how is it that a large collection of randomly...
  30. D

    What is the mathematical explanation behind red/blue shift caused by gravity?

    Can anyone supply me with the mathematics behind the energy gain/ loss as a photon travels through a gravitational potential difference?
  31. A

    How Do You Calculate Recoil Shift in Atomic Emissions?

    Homework Statement b) Calculate the recoil shift for the most energetic lyman line from a free H atom. c) Calculate the recoil shift for the emission of a 14.4keV gamma from a free atom of Fe-57. Homework Equations E = hc / \lambda = h \nu \Delta E = E^2 / 2mc^2 The Attempt...
  32. I

    Understanding Doppler Shift Equations for Calculating Object Velocity

    So I'm planning to start a project using the Doppler shift to calculate the velocity of a moving object. The problem is, I'm not sure which equations I should use, and I saw many different equations around the Internet. So are these equations correct? If not, can someone tell me what the...
  33. A

    Recoil shift from a free H atom.

    Homework Statement part b) Calculate the recoil shift for the emission of the most energetic Lyman line from a free atom of hydrogen. 2. The attempt at a solution My question isn't a physics one per se, I'm stuck on terminology. What is meant by "the most energetic Lyman line"? I'm use...
  34. e2m2a

    De Broglie wavelength shift in gravitational fields

    Photons are blue-shifted as they accelerate in free-fall toward the earth. When an electron or positron is conceptualized as a wave using de Broglie's equation, are the de Broglie wavelengths of the electron or positron shortened (blue-shifted) as they accelerate toward the Earth in free-fall...
  35. F

    Phase shift of tunneling particle

    Hi All, I'm sure this question has a trivial answer but for the life of me I've no idea :\ I am calculating (numerically because I am lazy and it scales/ports better to other cases) the phase shift of a particle in the non-rel Schrodinger equation tunneling through a potential step. This...
  36. T

    Can measurements of red shift be affected by the shape of spacetime?

    I have read on some threads that there are other possible shapes for spacetime and I wondered could any of these spacetime shapes, or their change over time, affect our measurement of red shift? Also does the matter density at the location where a photon is emitted relative to our own...
  37. nukeman

    Phase shift and sinusoidal curve fitting - Finding .

    Phase shift and sinusoidal curve fitting - Finding... Homework Statement "Find the period, amplitude, and phase shift of each function. Graph each function. Be sure to label key points" y = 4sin(2x - pi) Homework Equations The Attempt at a Solution So, I got...
  38. L

    Phase Shift effect on diode conduction time

    Ok, so let's say I have a simple half-wave rectifier like the one shown in the image below: http://img585.imageshack.us/img585/1904/unledmwc.jpg When it comes to the analysis of the circuit, during the positive cycle of the input voltage, the diode is forward biased and the output voltage...
  39. M

    Doppler shift for accelerated motion

    I was talking to one of my friends the other day about doppler effect and we went into the discussion of accelerating object and doppler effect. we both agreed that the frequency shift would vary in time. then we argued about the frequency shift for different observers and here is were it got...
  40. T

    Photon wavelength shift from gravitational lensing?

    The basic question is: will a photon traveling through a vacuum lose some of its energy due to interactions with gravity from a massive body? Gravitational lensing implies that the photon will change its initial direction but is its energy conserved (i.e. differences in blueshift/redshift...
  41. E

    Orbital Shift Hohmann transfer Isp Roket Fuel mass calculation

    1. The launch vehicle takes the moon orbiter to a circular orbit around the Earth at 300km altitude. The orbiter is to perform a Hohmann transfer to a Lunar orbit, entering into a circular lunar orbit at 50km altitude. The objective of the mission is to put a 200kg orbiter around the Moon. The...
  42. W

    Why is Refraction Explained as Phase Shift in Dielectrics?

    Hello. I've heard from someone that beam diffraction can be explained as the result of phase shift in a dielectric changing the pattern of maxima that we see as the "beam". I would love to see the math of this worked out- can anyone direct me to an appropriate resource? I've searched far and...
  43. G

    What Happens to the Fourier Transform When Functions Are Scaled and Shifted?

    If f(t) has the Fourier transform F(ω), what is the Fourier transform of the function g(t) = f(3t) − f(4t + 7)? Use the shift property and time scaling property of the Fourier transform to obtain your answer. I have no idea how to start, please help, thanks..
  44. bcrowell

    Universality of Doppler shift for energy of any massless field

    In "Does the inertia of a body depend upon its energy content?," http://fourmilab.ch/etexts/einstein/E_mc2/www/ , Einstein invokes a result from his 1905 SR paper, which is that the Doppler shift of a light wave's frequency D(v)=\sqrt{(1-v)/(1+v)} is also the factor by which its energy changes...
  45. F

    Shift Unleashed horrible texture problems

    I've been having texture problems and memory leaks for the PC version of need for speed shift unleashed. Sometimes the textures on the cars, and on the road, and in the sky, are all solid black. I had this same problem with star wars the force unleashed. Is there anything I can do to fix...
  46. J

    Shift left and right registers

    I have got what may be a silly question. I hope not. Using flip flops e.g. JK flip flops, counters can be constructed (modulus up and down counters). However when constructing shift registers data can be shifted left and right. When shifted right each the shift register could divide the initial...
  47. B

    Solving Doppler Shift to Calculate Cyclist's Speed

    Homework Statement A man riding his bicycle was caught driving through a red traffic light. The man was taken to court and trialled where he claimed he was cycling so quickly that the light had appeared to be green to him due to the Doppler effect. The prosecution accepted his excuse but...
  48. J

    Gravitational Red Shift at the center of a mass

    I understand we can calculate that gravitation is neutralized at the center of a mass - say, a planet or star (or anywhere within a spherical shell); I wondered if the GRS is also neutralized, or if being pervaded by gravity - however neutralized - the dilation of space-time persists therein.
  49. F

    Energy Dependence of Scattering Phase Shifts

    Hey all, This might seem like a strange/silly question but just humour me if you could... Is there any a-priori reason why a scattering phase shift should be linear in energy (energy of the incoming particle at infinity)? Are there examples of such shifts that have a different energy...
  50. T

    Flip-Flops and Shift Registers

    Homework Statement For the system of Fig. 1, construct a complete state diagram showing all 16 states of the system. Your diagram should have 16 circles, numbered 0000 through 1111, connected with arrows showing which state each state goes to after one tick of the clock. Interestingly, this...
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