MHT CET2007PhysicsWave Optics
The cell has an emf of 2 ~V and the internal resistance of this cell is 0.1 , it is connected to resistance of 3.9 , the voltage across the cell will be
Options
- A1.95 ~V
- B1.5 ~V
- C2 ~V
- D1.8 ~V
Correct answer
A. 1.95 ~V
Step-by-step solution
Key Idea When cell is giving current then the potential difference across its plates is less than its emf as potential drop across internal resistance occurs. When a cell of emf E is connected to a resistance of 3.9 , then the emf E of the cell remains constant, while voltage V goes on decreasing on taking more and more current from the cell. V=E-i r where r is internal resistance. array ll Also current & i= E R+r & V=E- ( E R+r ) r array Putting the numerical values, we have aligned E=2 V, r &=0.1 , R=3.9 V &=2- (