how do the cricket ball reverse swing?

Answer 1

by turning our hand

Answer 2

Steps
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Take a 20-30 over-old ball whose one side is still shining. Such a ball is usually heavier on the side of shine because of sweat put on it to shine, whereas the other side has gone through wear and tear without any repairs. This weight difference is what bowlers take advantage of.
Hold the ball along the seam, with shining side towards leg side and rough side towards the slips.
Flex your wrist along with the cricket ball such that the shining side is about 30 degrees downwards.
Bowl with your hands angled. The angle between your head and bowling hand at shoulder should be about 50-60 degrees. Bowl with your hand as much away from your head as possible.
Make sure that in the follow-through, your bowling hand goes between your body and the stumps (on either side of your body.)



Tips
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Shine the ball very much and make the other-rough side as rough as possible. To test if the ball is ready for a reverse swing, just throw the ball with straight seam to a fielder and if the ball swings towards the shining surface, then it's ready to dance the batsman out.
You must pitch the ball up, reverse swinging yorkers can be devastating - as Waqar Younis proved at his peak. Few bowlers can reverse a ball away from the bat - hence the success of Simon Jones and Andrew Flintoff against the Australians.
Practise reversing an old, prepared ball in the nets. It's not going to happen by magic in the middle if you haven't practised it thoroughly.



Warnings
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Wrist position and follow-through are important.
Using a blade, metal or even fingernails to quicken the process of creating a rougher surface is always and in every circumstance illegal and not in the spirit of the game. If you get caught 'ball tampering' by the umpires you'll get banned from the game.

Answer 3

Check the following link for details:

http://www.soest.hawaii.edu/GG/STUDENTS/jfoster/reverse.html