
The emf of a cell is and its internal resistance is r. Its terminals are connected to a resistance R. The potential difference between the terminals is 1.6 V for and 1.8 V for . Then
A.
B.
C.
D.
Answer
476.1k+ views
Hint:You can use Kirchhoff’s law to determine the current flowing through the circuit. The potential difference across the terminals of the battery is equal to the potential difference across the resistance. Write the two equations using this fact and solve them simultaneously to determine the internal resistance of the battery.
Formula used:
Potential difference, ,
V is the voltage, I is the current and R is the resistance.
Complete step by step answer:
We know the current flowing through the circuit containing a resistor R and a battery of internal resistance r is given as,
, where, is the emf of the battery.
We can see the current flowing through resistance is and we know that the same current is provided by the battery. Therefore, we can write, the potential difference across the battery is equal to the potential difference across the resistance .
Substituting in the above equation, we get,
…… (1)
Again, we have given that the potential difference between the terminals is 1.8 V when . Therefore, we can write,
…… (2)
Equating equation (1) and (2), we get,
Substituting in equation (1), we get,
So, the correct answer is option B.
Note:The potential difference across the battery terminals is the product of current supplied by the battery and resistance of the circuit and not the internal resistance of the battery. In many cases, the internal resistance of the battery is negligible compared to the external resistance of the circuit and therefore, we often neglect the internal resistance. But it should not be neglected if the external resistance of the battery is of few ohms.
Formula used:
Potential difference,
V is the voltage, I is the current and R is the resistance.
Complete step by step answer:
We know the current flowing through the circuit containing a resistor R and a battery of internal resistance r is given as,
We can see the current flowing through resistance
Substituting
Again, we have given that the potential difference between the terminals is 1.8 V when
Equating equation (1) and (2), we get,
Substituting
So, the correct answer is option B.
Note:The potential difference across the battery terminals is the product of current supplied by the battery and resistance of the circuit and not the internal resistance of the battery. In many cases, the internal resistance of the battery is negligible compared to the external resistance of the circuit and therefore, we often neglect the internal resistance. But it should not be neglected if the external resistance of the battery is of few ohms.
Recently Updated Pages
Master Class 12 Business Studies: Engaging Questions & Answers for Success

Master Class 12 Economics: Engaging Questions & Answers for Success

Master Class 12 Maths: Engaging Questions & Answers for Success

Master Class 12 Biology: Engaging Questions & Answers for Success

Master Class 12 Physics: Engaging Questions & Answers for Success

Master Class 12 English: Engaging Questions & Answers for Success

Trending doubts
A deep narrow valley with steep sides formed as a result class 12 biology CBSE

a Tabulate the differences in the characteristics of class 12 chemistry CBSE

Why is the cell called the structural and functional class 12 biology CBSE

Which are the Top 10 Largest Countries of the World?

Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE

Derive an expression for electric potential at point class 12 physics CBSE
