Meter Bridge - Practice Questions & MCQ

Meter bridge

• It is used to find the resistance of a given wire using a meter bridge and hence determine the specific resistance of its materials.
• It works on the principle of Wheatstone's bridge
• The meter bridge arrangment is shown in the above figure. The wire connected between A and C is of 1 merer length and have uniform crossection. A constant current is passed through the wire AC  so that potential of the wire is proportional to the length of the wire. R is the known resistance which is selected from the resistance box. S is the unknown resistance whose value can be measured. The arrangment also has a galvanometer with a jokey
• We will slide the galvanometer through wire AC so as to obtain null deflection in the galvanometer. Let B is the point on AC where null deflection is obtained and length AB=. Pand Q resistance of the portion AB and BC respectively then then by principle of Wheatstone's bridge

         $\frac{P}{Q}=\frac{R}{S} \Rightarrow S=\frac{(100-l)}{l} R$