Editing Gravitational Lensing

Questions in this category have been asked by PJ, MT and SR

*How can you use gravitational lensing to determine H0?
**What is the deflection of light by sun using newtonian mechanics? (calculate it, do the integral)
**Compare it with the GR result

*What kind of objects can cause gravitational lensing?
**what's the smallest thing we know that causes lensing?

*"Do you know anything about Gravitational Lensing? Write down any equation related to lensing." (SR)
*How do you determine the magnification of a gravitationally lensed image from the lens equation? (SR)

*How would one calculate the deflection angle of light using GR? (SR)
*Write down the lens equation. (SR)
*What is a typical size of an Einstein radius? (RS? SR? I can't remember who asked.)
*In microlensing, how does one detect a lensing event, given that one does not see a clear Einstein ring?  (SR,MT)
**How is this effect related to the lensing potential? (SR, MT)

*Write down the lens equation for an isothermal sphere and a point mass.  What is the Einstein radius?
** How would you compute the magnification?  How would you do this without any equations? (SR)

*What is the cross section for a stellar mass lensing event, a planet sized lensing event?  Why do we see planet lensing events?  (SR)

*What are the observational difficulties of weak lensing measurements? (MT)

[[Astrophysics]]
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 *What are the observational difficulties of weak lensing measurements? (MT)
-*Why is there a sweet spot for gravitational lenses around redshift .7?
-*What is the Newtonian lensing result and how does it differ from the relativistic result?
-*Are the D's in the formula for the Einstein radius angular diameter distances, luminosity distances, or comoving distances?
 [[Astrophysics]]