physics

An electron is accelerated from rest through a potential difference that has a magnitude of 2.90 × 107 V. The mass of the electron is 9.11 × 10-31 kg, and the negative charge of the electron has a magnitude of 1.60 × 10-19 C. (a) What is the relativistic kinetic energy (in joules) of the electron? (b) What is the speed of the electron? Express your answer as a multiple of c, the speed of light in a vacuum.

asked by PLEASE AND THANK YOU
  1. relativistic KE=Voltage*charge

    to find the speed,

    relastivistic KE=restmass*c*gamma

    gamma=(1/sqrt(1-(v/c)^2) -1)

    so take relavitic KE, divide by restmass, then divide by speed of light.
    result=gamma

    Now ignore the -1 in the gamma, look at it later. If v is approaching c, it can be ignored.

    square both sides (ignoring the -1)
    solve for v in terms of c. If v/c is within .5 or greater, use that v, it is pretty accurate. If v/c is greater than .5, you have to consider the -1 in gamma. You can do that by expanding the gamma with the binomial expansion, and there are programs to do that, and I am told calculators to do it. I would not relish doing more than a few terms by hand.

    posted by bobpursley

Respond to this Question

First Name

Your Answer

Similar Questions

  1. Physics

    An electron is accelerated from rest through a potential difference that has a magnitude of 2.70 × 107 V. The mass of the electron is 9.11 × 10-31 kg, and the negative charge of the electron has a magnitude of 1.60 × 10-19 C.
  2. Physics

    A uniform electric field of magnitude 370 N/C pointing in the positive x-direction acts on an electron, which is initially at rest. The electron has moved 2.70 cm. (a) What is the work done by the field on the electron? J? (b)
  3. math

    the electron beam in a television tube consists of electrons accelerated from rest through a potential difference of about 20000v.what is the speed of the electrons?(ignore relativistic effects).electron rest mass is 9.11 X
  4. Physics

    A uniform electric field of magnitude 395 N/C pointing in the positive x-direction acts on an electron, which is initially at rest. The electron has moved 3.40 cm. What is the work done by the field on the electron? What is the
  5. Science

    Use the following values for mass and charge: an electron has mass me = 9.11×10-31 kg and charge -e, a proton has mass mp = 1.67×10-27 kg and charge +e, an alpha particle has mass malpha = 6.65×10-27 kg and charge +2e, where e
  6. Science

    Use the following values for mass and charge: an electron has mass me = 9.11×10-31 kg and charge -e, a proton has mass mp = 1.67×10-27 kg and charge +e, an alpha particle has mass malpha = 6.65×10-27 kg and charge +2e, where e
  7. Physics pls help

    An electron is accelerated by a 6.4 kV potential difference. The charge on an electron is 1.60218 × 10^−19 C and its mass is 9.10939 × 10^−31 kg. How strong a magnetic field must be experienced by the electron if its
  8. Physics

    An electron with a mass of 9.11 *10^31 Kg is accelerated from rest across a set if parallel plates that have a potential difference of 150 v and are separated by 0.80 cm A) determine the kinetic energy of the electron after it
  9. Physics

    An electron has an initial speed of 4.00×106 m/s. What potential difference (sign and magnitude) is required to bring the electron to rest?
  10. Physics

    Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the naturally occuring electrons is removed. The radius of the orbit is 2.26 × 10-11 m.

More Similar Questions