How will the position of null point in a potentiometer change with increase in resistance of its wire?

So as the resistance $R$ increases the resistance of the wire $AB$ increases. Hence the current flow in the wire will decrease and the potential drop per unit length of the wire will also decrease, so a greater length of wire is required to find the null point. Thus, the null point will shift towards the point $B$.

What happens at null point in potentiometer?

The balancing point or null point of the potentiometer is the point on the slide wire when the galvanometer shows zero deflection. The balance point is found to determine the unknown voltage of the cell connected to the cell.

How does cross section affect resistance?

Resistance is inversely proportional to cross-sectional-area. The bigger the cross sectional area of the wire the greater the number of electrons that experience the ‘electric slope’ from the potenetial difference.

What does increasing the cross section of a wire do?

More collisions mean more resistance. In the same manner, the wider the wire, the less resistance that there will be to the flow of electric charge. When all other variables are the same, charge will flow at higher rates through wider wires with greater cross-sectional areas than through thinner wires.

How will the position of null point change?

So, the null point would shift towards right (i.e., towards B). (ii) By decreasing resistance S, the terminal potential difference V=E1+rSacross cell decreases, so balance is obtained at small length i.e., point will be obtained at smaller length. So, the null point would shift towards left (i.e., towards A).

How is the position of balance point affected in an experiment with potentiometer if the length of potentiometer wire is increased?

If the length of a potentiometer wire is increased the balance point will increase. The balance point would keep increasing if the length of the potentiometer wire would be increased. A potentiometer is a three-terminal resistor that uses a sliding or rotating contact to form an adjustable voltage divider.

What is null point method?

[′nəl ‚meth·əd] (engineering) A method of measurement in which the measuring circuit is balanced to bring the pointer of the indicating instrument to zero, as in a Wheatstone bridge, and the settings of the balancing controls are then read. Also known as balance method; zero method.

What will be the effect on null point if only the current through potentiometer wire is decreased?

If the current in the wire of potentiometer is decreased, the potential gradient will decrease and hence the position of zero deflection will occur at longer length.

What happens to resistance when area of cross section is decreased?

The resistance of a conductor is inversely proportional to its area of cross section. i.e., Resistance will be reduced to half.

How does the increase of length and cross section area of a conductor affect its resistance?

The resistance is directly proportional to the length of the wire, the longer the wire the greater the resistance. Well the longer the wire the more collisions the electrons will have with the atoms in the way from one end of the wire to the other. Therefore the resistance will increase as the length increases.

How can the sensitivity of potentiometer be increased?

The sensitivity of the potentiometer can be increased by decreasing the potential gradient. i.e., by increasing the length of the potentiometer wire. Sensitivity of potentiometer can be increased by: Increasing the length of the potentiometer wire.

Is there any current in the potentiometer wire at the null point?

Now, is there any current in the potentiometer wire at the null point? If by potentiometer wire, you mean the resistance element, the answer is yes. Let the current, from left to right, through the section of the potentiometer resistance from $A$ to $B$, $R_{AB}$ be labelled $I_{AB}$.

What is the principle of potentiometer?

(i) Principle of Potentiometer The potential drop across the length of a steady current carrying wire of uniform cross-section is proportional to the length of the wire. (a)We use a long wire to have a lower value of potential gradient (i.e a lower “least count” or greater sensitivity of the potentiometer.

What is the potential gradient of a potentiometer?

In such a case, the p.d. per unit length of the wire is constant and called the potential gradient of the wire or voltage drop across the wire. The e.m.f. of the cell connected across the potentiometer wire should b greater than the e.m.f. to be compared.

How do you double the length of a potentiometer wire?

You can double the length of the wire by stretching it, by bonding another piece the same length to the existing length, or replacing it with another piece of resistive wire…. but that doesn’t make it part of the potentiometer.