How will the balancing length of a potentiometer be affected if resistance in the primary cell is increased or decreased?
Will the balancing length change if a resistance is introduced before the jockey ?
To understand how the balancing length of a potentiometer is affected by changes in resistance, let's first go over the basics of a potentiometer. A potentiometer is a device used to measure potential difference (voltage) accurately.
In a potentiometer setup, a primary cell is connected to a resistor wire, also known as a potentiometer wire. The potentiometer wire has a uniform resistance per unit length. A sliding contact called a jockey is used to make electrical contact along the wire. When the jockey is moved along the wire, it can establish a point of balance at which the potential difference across the jockey is zero.
1. Effect of increased or decreased resistance in the primary cell:
If the resistance in the primary cell is increased, the potential difference across the cell will increase. Consequently, the potential difference across any point on the potentiometer wire will also increase. As a result, the balancing length of the jockey will decrease since it needs to be moved closer to the cell to maintain the zero potential difference across the jockey.
On the other hand, if the resistance in the primary cell is decreased, the potential difference across the cell will decrease. Hence, the potential difference across any point on the potentiometer wire will also decrease. Consequently, the balancing length of the jockey will increase as it needs to be moved farther away from the cell to maintain the zero potential difference.
2. Effect of introducing a resistance before the jockey:
If a resistance is introduced before the jockey, it will affect the total resistance in the circuit. As a result, the potential difference across the jockey and the balancing length will change.
a. If the resistance introduced is increased, the total resistance in the circuit increases. Consequently, the potential difference across the jockey decreases, and the balancing length increases. The jockey needs to be moved farther away from the cell to maintain the zero potential difference.
b. If the resistance is decreased, the total resistance in the circuit decreases. This leads to an increase in potential difference across the jockey and a decrease in balancing length. The jockey needs to be moved closer to the cell to maintain the zero potential difference.
In summary, the balancing length of a potentiometer is affected by changes in the resistance of the primary cell or any resistance introduced before the jockey. Increased resistance in the primary cell or a resistance introduced before the jockey will decrease the balancing length, while decreased resistance will increase the balancing length.