JEE Main2018PhysicsCurrent ElectricityActual
In a meter bridge as shown in the figure, it is given that resistance Y = 12.5 Ω and that the balance is obtained at a distance 39 . 5 cm from end A (by jockey J ). After interchanging the resistances X and Y a new balance point is found at a distance l 2 from end A . What are the values of X (in Ω ) and l 2 ?
Options
- A19 . 15   Ω and 39 . 5   cm
- B8 . 16   Ω and 60 . 5   cm
- C8 . 16   Ω and 39 . 5   cm
- D19 . 15   Ω and 60 . 5   cm
Correct answer
B. 8 . 16   Ω and 60 . 5   cm
Step-by-step solution
For a balanced meter bridge, ( y )×​ 39.5 = x × 100 - 39.5 , x = 12.5 × 39.5 60.5 = 8.16   Ω . When x  and  y are interchanged l 1 and ( 100 − l 1 ) will also interchange, l 2 = 60. 5   cm .