Part 1Metre bridge has plates instead of wires because wires provide more resistance than plates as plates have more area of cross section than wires which can be equated asV=IR; but I =neAVdtherefore, V=neAVd*ROr , R=V/(neAVd),Hence R proportional to 1/AThus, with increase in Area(A),resistance (R) decreases. Part 2Metre bridge is actually based on the principle of Wheatstone bridge thus both are same. And it is based on balanced reading of galvanometer which measures resistance by proportion of resistances.so please check the question and understand the question and concept of wheatstone bridge.I think answer will get clear.
