MHT CET202313 May 2023Morning ShiftPhysicsElectrostaticsActual
Two cells E ₁ and E ₂ having equal EMF ' E ' and internal resistances r₁ and r₂ (r₁>r₂ ) respectively are connected in series. This combination is connected to an external resistance ' R '. It is observed that the potential difference across the cell E₁ becomes zero. The value of ' R ' will be
Options
- Ar₁-r₂
- Br ₁+ r ₂
- Cr ₁- r ₂ 2
- Dr₁+r₂ 2
Correct answer
A. r₁-r₂
Step-by-step solution
The total current in the circuit is I= 2 E r₁+r₂+R ....(Given cells are in series, E + E =2 E ) Now the potential drop across the first cell is array ll & V ₁= E - Ir ₁=0 & E - ( 2 E r ₁+ r ₂+ R ) r ₁=0 & 2 E r ₁+ r ₂+ R = E r ₁ 2 r ₁= r ₁+ r ₂+ R & R = r ₁- r ₂ array