Expert: Jane Tang - 12/2/2006

Question
Dear Jane,
I am a student from Israel. I'm doing a school project about "Black Holes", and i have a question I would like to ask you.
I have read an article about black holes, which said black hole have an extremely strong gravitational field.
I would like to ask you, what causes the strong gravitational field around the black hole?

I would really appreciate you taking the time to answer my question.

Yours,
Alex.  

Answer
I am very glad to answer your question. The strong gravitational field about the black hole is generated by the huge mass of the black hole (BH). The gravitational force is proportional to the mass of the BH and 1/(r^2), in which r is the distance between the observer and the center of BH. Since r is small and mass is huge, we have strong gravitational field around BH.

    cheers,
       jane