A light source recedes from an observer with a speed νs that is small compared with c. (a) Show that the fractional shift in the measured wavelength is given by the approximate expression
This phenomenon is known as the redshift because the visible light is shifted toward the red. (b) Spectroscopic measurements of light at λ = 397 nm coming from a galaxy in Ursa Major reveal a redshift of 20.0 nm. What is the recessional speed of the galaxy?
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Chapter 39 Solutions
Physics for Scientists and Engineers, Technology Update (No access codes included)
- Suppose the primed and laboratory observers want to measure the length of a rod that rests on the ground horizontally in the space between the helicopter and the tower (Fig. 39.8B). To derive the length transformation L = L (Eq. 39.5), we had to assume that the positions of the two ends were determined simultaneously. What happens to the length transformation equation if both observers measure the end below the helicopter at one time t1 and the other end at a later time t2?arrow_forward(a) What is the effective accelerating potential for electrons at the Stanford Linear Accelerator, if =1.00105 for them? (b) What is their total energy (nearly the same as kinetic in this case) in GeV?arrow_forwardThe light from a heated atomic gas is shifted in frequency because of the random thermal motion of light-emitting atoms toward or away from an observer. Estimate the fractional Doppler shift (f/f0), assuming that light of frequency f0 is emitted in the rest frame of each atom, that the light-emitting atoms are iron atoms in a star at temperature 6000 K, and that the atoms are moving relative to an observer with the mean speed =8kBTm Must we use the relativistic Doppler shift formulas f=f01/c1/c for this calculation? Such thermal Doppler shifts are measurable and are used to determine stellar surface temperatures.arrow_forward
- m=9arrow_forwardAn electron-positron collider runs with symmetric beam energies of E(e+) = E(e¯) = 102 GeV. At each orbit AE = 2.2 GeV has to be replaced for each beam particle by the accelerating units. The accelerator has 24 units available; each unit can replace an energy of AE = 100 MeV per orbit. a) State the mechanism responsible for the energy loss and state how the energy loss per orbit scales with the beam energy. b) The researchers want to create the Standard-Model Higgs boson but don't know its mass yet. Argue why the production rate via the direct process ete →H is negligible and name the process which can be used instead. Draw a Feynman diagram of this process. [6 marks]arrow_forwardA galaxy G is moving away radially with speed with respect to an observer O. The relation between X, the wavelength of light emitted at G, and λo, the wavelength observed at O, is 入。 λ = λe λε 1+B 1- B' = where ẞ v/c (c is the speed of light). For ẞ < 1 find a power series expansion of the above formula up to and including terms of order ẞ³.arrow_forward
- Consider a region where the following electric and magnetic fields are present: E = 12.52 ax + 19.68 ay + 18.72 az volts per meter and B = -12.00 ax + 18.86 ay + 18.27 az teslas. If a 1.38-coulomb charge is moving at a speed of 2.73 meters per second in the -y-direction, determine the magnitude of the Lorentz force in newtons.arrow_forwardA linear particle accelerator using beta particles collides electrons with their anti-matter counterparts, positrons. The accelerated electron hits the stationary positron with a velocity of 19 x 106 m/s, causing the two particles to annihilate.If two gamma photons are created as a result, calculate the energy of each of these two photons, giving your answer in MeV (mega electron volts), accurate to 1 decimal place. Take the mass of the electron to be 5.486 x 10-4 u, or 9.109 x 10-31 kg.Note: Assume that the kinetic energy is also converted into the gamma rays, and is included in the two photons.arrow_forwardQuasars are faint, distant sources of radio waves. (Quasar is short for "quasi-stellar source." They are so named because, like a star, they appear to the astronomer to be pointlike.) From the shift in the frequency of their emitted light toward the red, called the "redshift," we know that quasars are moving very fast. Astronomers observe that the more distant an object is from the earth, the faster it moves. In this way they determine that quasars are billions of light years from earth. To be visible at this great distance, quasars must have enormous luminosity. Typically a quasar radiates energy at a rate on the order of 1040 W, roughly 1014 times greater than the sun or 40 times greater than the most luminous galaxy. At what rate is rest mass being consumed to produce this much radiation? Quasar 3C-273arrow_forward
- Quasars are faint, distant sources of radio waves. (Quasar is short for "quasi-stellar source." They are so named because, like a star, they appear to the astronomer to be pointlike.) From the shift in the frequency of their emitted light toward the red, called the "redshift," we know that quasars are moving very fast. Astronomers observe that the more distant an object is from the earth, the faster it moves. In this way they determine that quasars are billions of light years from earth. To be visible at this great distance, quasars must have enormous luminosity. Typically a quasar radiates energy at a rate on the order of 1040 W, roughly 1014 times greater than the sun or 40 times greater than the most luminous galaxy. At what rate is rest mass being consumed to produce this much radiation?arrow_forwardAn electron of charge ee of modulus v completes a semicircle of radius R due to a magnetic field of modulus B, placed perpendicular to v. What is the work W done by the Lorentz force? O (a) W = π eVBR/2 J O (b) W = 0J O (C) W=2 TT eVBR J O (d) W = π eVBR Jarrow_forwardA linear particle accelerator using beta particles collides electrons with their anti-matter counterparts, positrons. The accelerated electron hits the stationary positron with a velocity of 29 x 106 m/s, causing the two particles to annihilate.If two gamma photons are created as a result, calculate the energy of each of these two photons, giving your answer in MeV (mega electron volts), accurate to 1 decimal place. Take the mass of the electron to be 5.486 x 10-4 u, or 9.109 x 10-31 kg.arrow_forward
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