during reverse biasing,since depletion region is very large,majority carriers cannot conduct as they cannot travel large distance but minority carriers can conduct. how is it possible since minority carriers also has to travel the same distance.

During reverse bias,

 

The electrons which had migrated across from the N to the P region in forming of the deplition layer have now reached equilibrium. Other electrons from the N region cannot migrate because they are repelled by the negative ions in the P region and attracted by the positive ions in the N region.

 

But in case of minority charge carrieres the senario is opposite.

Electrons in the P region are attracted by the positive ions in the N region. In the same way, holes in the N region are attracted by the negative ions in the P region.

 

Hence due to this attractive columb force minnority charge carriers are able to cross the deplition region.

 

But due to repulsive columb force majority charge carriers can not cross deplition region.