In a potentiometer the null point is received at 7th wire. If now we have to change the null point at \(9\text{th}\) wire, what should we do?
In a potentiometer the null point is received at 7th wire. If now we have to change the null point at \(9\text{th}\) wire, what should we do?
- Attach resistance in series with battery
- Increase resistance in main circuit
- Decrease resistance in main circuit
- Decrease applied emf
The Correct Option is B
Solution and Explanation
The working of potentiometer is based on the fact that the fall of potential across any portion of the wire is directly proportional to the length of that portion provided the wire is of uniform area of cross-section and a constant current is flowing through it. To shift the balance point on higher length, the potential gradient of the wire is to be decreased. The same can be obtained by decreasing the current of the main circuit, which is possible by increasing the resistance in series of potentiometer wire.
Therefore, the correct option is (B): Increase resistance in main circuit
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Concepts Used:
Current Electricity
Current electricity is defined as the flow of electrons from one section of the circuit to another.
Types of Current Electricity
There are two types of current electricity as follows:
Direct Current
The current electricity whose direction remains the same is known as direct current. Direct current is defined by the constant flow of electrons from a region of high electron density to a region of low electron density. DC is used in many household appliances and applications that involve a battery.
Alternating Current
The current electricity that is bidirectional and keeps changing the direction of the charge flow is known as alternating current. The bi-directionality is caused by a sinusoidally varying current and voltage that reverses directions, creating a periodic back-and-forth motion for the current. The electrical outlets at our homes and industries are supplied with alternating current.