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B Black Hole as a Gravitional Lens

  1. Jun 10, 2017 #1

    I want to know about bending light property of a black hole. The bending angle formula
    [​IMG] does not tell that r is perpendicular distance to light. Does a black hole
    having mass M has different bending power than the body having the same mass M?
    What about region around a black hole to bend a light ray? Can we use the above formula in this region?
  2. jcsd
  3. Jun 10, 2017 #2


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    Staff: Mentor

    The physics in the vacuum outside an ordinary spherically symmetric object of a given mass is the same as the physics in the vacuum outside of a black hole of the same mass. For example, the earth's orbit would be unchanged if we replaced the sun with a one-solar-mass black hole, and the same is true of light deflection by the sun.
  4. Jun 19, 2017 #3
    Thanks for your information. I am interested in deflection pattern of light by black hole. Is there any difference in the deflection angle
    of light by black hole if :
    r is the perpendicular distance from the black hole
    & r is the angular distance from the black hole
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