Previous Year Question
Black-hole is
a flight recorder in aeroplane
a spot on the sun
a place in Antarctica
a collapsed star
Correct Answer: D
Detailed Solution
A Black Hole is a region of space where gravity is so intense that, beyond a certain boundary, even light cannot escape.
The usual formation mechanism of a stellar-mass Black Hole involves the gravitational collapse of a very massive star. When such a star exhausts the nuclear fuel in its core, it may no longer generate enough pressure to resist gravity. Its core can collapse rapidly and, under suitable conditions, form a Black Hole. NASA has also described observational evidence of massive stars collapsing directly into Black Holes.
A major boundary of a Black Hole is called the Event Horizon. Within this boundary, escape would require a velocity greater than the speed of light; hence, no electromagnetic signal can escape.
A Black Hole is not simply a “black star” in the ordinary sense. It is not a normally shining stellar object but an extremely compact gravitational object. Scientists generally detect it indirectly through its effects on surrounding matter, radiation from an accretion disk and gravitational influence.