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  1. S

    How far away is it?

    No, that was the exact question.
  2. S

    De Broglie hypothesis problem

    According to the de Broglie hypothesis, which of the following statements is applicable to the wavelength of a moving particle?
  3. S

    What speed do the electrons have when they strike the screen?

    No, I just need the exact formula then I will know what to do from there.
  4. S

    Just curious

    What is the relationship between the wave function ψ(r,t) of a particle and the probability of finding the particle at position r at time t?
  5. S

    Within what time interval can we create and destroy an electron-positron pair without

    The rest energy of an electron is 0.511 MeV = 8.2 x10-14 J. A positron is an electron with positive charge and the same rest energy. Within what time interval can we create and destroy an electron-positron pair without worrying about the conservation of energy? h = 6.626 × 10-34 J s.
  6. S

    What speed do the electrons have when they strike the screen?

    These are the possible answers. a. 0.55c. b. 0.09c. c. 0.30c. d. 0.90c.
  7. S

    How far away is it?

    The nearest star to the Sun is Proxima Centauri, a very faint component of the Alpha Centauri system. It takes light 4.2 years to reach us from Proxima. In the light's own frame, how far away is it?
  8. S

    What speed do the electrons have when they strike the screen?

    In a typical color television tube, the electrons are accelerated through a potential difference of 25,000 Volts. What speed do the electrons have when they strike the screen? (qe = 1.6 x10-19 C, me = 9.1 x10-31 kg)
  9. S

    Soap film having index of refraction

    What is the minimum (non-zero) thickness of a soap film having index of refraction 1.46, with air on both sides, that transmits virtually 100% of 500 nm light incident along the normal? a. 345 nm. b. 86 nm. c. Any thickness transmits 100%. d. 172 nm. I used...
  10. S

    Young's double slit

    What happens to a light wave when it is reflected off the surface of a material with a higher index of refraction? a. It reflects with its phase shifted by π. b. It reflects with its phase shifted by π/2. c. The phase shift is proportional to the angle of reflection. d. It...
  11. S

    Right hand rule?

    thank you very much!!
  12. S

    Right hand rule?

    ok so my palm faces east since it goes left to right, my thumb is pointing down. but down would mean positive, so im assuming it goes to the top right?
  13. S

    Right hand rule?

    Assume that a uniform magnetic field is directed into this page. If an electron is released with an initial velocity directed from the left edge to the right edge of the page, which of the following describes the direction of the resultant force acting on the electron? I think it would come...
  14. S

    Change in internal energy in air

    ok, thank you very much its appreciated
  15. S

    Classic acceleration?

    thank you very much, i just solved it
  16. S

    Δp/Δt = −ΔEP/Δs why a negative?

    Why is there a minus sign in the formula Δp/Δt = −ΔEP/Δs? Is it because the objects are accelerated toward or away from a higher potential, or is it something else? If anyone could help me, thank you!
  17. S

    Increase in entropy

    Thank you very much, its very appreciated.
  18. S

    Change in internal energy in air

    If we apply 300 kJ of heat to 2500 moles of air at constant pressure, what is the change in internal energy? So far i think I use the equation: (f/x)nkT, but I don't know how to calculate the degrees of freedom and whether I do or not, and whether or not to calculate the number of moles by...
  19. S

    Increase in entropy

    2.1 x107 kg of ice and snow at 265 K slides 0.55 km (vertical distance) down a mountain in an avalanche. What is the increase in entropy? I am having trouble finding an equation on how to solve this problem. If anyone could help me at all, thank you.
  20. S

    Classic acceleration?

    What is the classical acceleration of the electron in a hydrogen atom, separated from the proton by 5.29 x10^−11 m? Electron mass = 9.11 x10^−31 kg. I am having a problem finding an equation for this problem, if anyone could help, it would be appreciated thank you!
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