Student Kelvin Double Bridge

It is used to measure unknown value of low resistance. Variable arm of bridge consist of decade dial of 0.1 ohms in series with a slide wire of 0.1ohms divided into 100 equal divisions. RATIO BOX :Two set of ration arms are provided and selected simultaneously by lead of galvanometer giving multiplying factor of 100,10,1,0.1 and 0.01 PRESS KEY :A battery press key is proved to bring the batter into circuit.