Question

explain right hand thumb rule.

Answer 1

 a rule in electricity: if the thumb, the forefinger, and the middle finger of the right hand are bent at right angles to one another with the thumb pointed in the direction of motion of a conductor relative to a magnetic field and the forefinger in the direction of the field, then the middle finger will point in the direction of the induced electromotive force 

Answer 2

$\tt{ \: right \: hand \: thumb \: rule \: }$