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EMF & Internal Resistance of Cells Video Lecture | Physics Class 12 - NEET

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FAQs on EMF & Internal Resistance of Cells Video Lecture - Physics Class 12 - NEET

1. What is the relationship between EMF and internal resistance in a cell?
Ans. The EMF (electromotive force) of a cell represents the maximum potential difference it can provide when no current is flowing. The internal resistance of a cell, on the other hand, represents the resistance to the flow of current within the cell itself. The relationship between EMF and internal resistance can be described using Ohm's Law, which states that the voltage across a resistor is equal to the current flowing through it multiplied by its resistance. In the case of a cell, the voltage across its terminals (EMF) will decrease as the current increases due to the voltage drop across the internal resistance.
2. How does the internal resistance of a cell affect its performance?
Ans. The internal resistance of a cell plays a significant role in determining its performance. As the internal resistance increases, the voltage across the terminals of the cell decreases for a given current. This leads to a decrease in the overall power output of the cell. Additionally, a higher internal resistance results in a greater voltage drop within the cell itself, leading to a higher rate of energy dissipation and potentially shorter battery life. Therefore, a lower internal resistance is generally desirable for optimal cell performance.
3. Can the internal resistance of a cell be reduced?
Ans. The internal resistance of a cell is primarily determined by its construction and the materials used. In some cases, it is possible to reduce the internal resistance by optimizing the design or using more conductive materials. However, there is a limit to how low the internal resistance can be reduced, as it is inherent to the cell's construction. Additionally, factors such as temperature and age can also affect the internal resistance. Therefore, while it may be possible to reduce the internal resistance to some extent, it is not always feasible or practical.
4. How does the internal resistance of a cell impact its ability to deliver high currents?
Ans. The internal resistance of a cell affects its ability to deliver high currents by causing a voltage drop within the cell itself. As the current increases, the voltage drop across the internal resistance increases proportionally, leading to a decrease in the voltage available across the cell terminals. This voltage drop limits the maximum current that can be drawn from the cell. Therefore, a cell with a higher internal resistance will have a reduced ability to deliver high currents compared to a cell with a lower internal resistance.
5. Is there a relationship between the internal resistance of a cell and its lifespan?
Ans. The internal resistance of a cell can indirectly affect its lifespan. A higher internal resistance leads to a greater voltage drop within the cell, resulting in a higher rate of energy dissipation and potentially reducing the cell's overall capacity. This can lead to a shorter battery life. Additionally, a higher internal resistance can also cause increased heat generation within the cell, which can further accelerate degradation and reduce lifespan. However, it is important to note that various other factors, such as usage patterns, environmental conditions, and cell chemistry, also play significant roles in determining the lifespan of a cell.
98 videos|387 docs|104 tests
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