A pair of L shape dowsing rods can be used to detect positive and negative waves. A wave can be a sound or thought wave.A positive wave is one which is good for us and the other which is not.For example if somebody shouts at us using filthy language then negative sound waves are propagated in the environment and this negative waves does not align with our culture and net result is a disaster.On the other hand when someone speaks good about us positive sounds waves are propagated and we feel happy.The same principle apples when we think bad or feel jealous about another person or if we are in the company of a person with negative thoughts.This gives us an idea of positive and negative waves.
If the 2 L shaped rods are brought in front of our gurus or Gods these rods will deflect showing positive waves.In one of the instance when the L shaped rods was brought in front of the picture of Brahma Sree Neelakanta Gurupadar,Guru of Jagadguru Swami Sathyananda Saraswathi Tiruvadikal the rods deflected to an angle of 180 degrees and remained there even when the guru's picture was removed.This shows how divine was swamiji's guru and also whenever we think of our gurus or Gods positive waves are formed in the environment and provides a healthy atmosphere.
The same L shaped rods can be checked for negative waves.The easiest one is bringing it in front of an orchid and the rods will cross showing negative waves and instead of Orchid use Tulsi (Ocimum tenuiflorum ) leaf and it will show positive waves.Tulsi or Tulasi is a sacred plant for Hindus.
Listen to the concept from Swamiji's own words below.