Mell What is null deflection in Wheatstone bridge?
The Wheatstone bridge works on the principle of null deflection, i.e. the ratio of their resistances are equal, and no current flows through the galvanometer. The bridge is very reliable and gives an accurate result.
Why Wheatstone bridge is a null method?
The Wheatstone bridge is a null measurement device for calculating resistance by balancing potential drops in a circuit. (See Figure 4.) The potential difference between points b and d is then zero, meaning that b and d are at the same potential.
How do you use Wheatstone bridge to find unknown resistance?
The unknown resistance Rx is to be measured; resistances R1, R2 and R3 are known, where R2 is adjustable. When the measured voltage VG is 0, both legs have equal voltage ratios: R2/R1 = Rx/R3 and Rx= R3R2/R1.
Which meter is used a null detector in Wheatstone bridge?
In Wheatstone bridge method, instrument used as null detector is Galvanometer.
What is the null deflection method?
Null deflection point is the point at which the galvanometer shows no deflection. In the potentiometer to get the zero reading in galvanometer joe key is moved along the length of the potentiometer wire. At a particular point the null defection is obtained and that length is known as balancing length.
What are the advantages of null point?
In a Wheatstone bridge the main advantage of null point method is that the resistance of galvanometer does not affect the balance point, there is no need to determine current in resistances and the internal resistance of a galvanometer. It is convenient and easy method for observer.
What is null point in meter bridge?
The metre bridge, also known as the slide wire bridge consists of a one metre long wire of uniform cross sectional area, fixed on a wooden block. As the jockey slides over the wire AC, it shows zero deflection at the balancing point (null point).
Where should the null point is ideally found?
The null point should be obtained preferably at the middle one-third portion of the wire of meterbridge so as to get maximum accuracy. In this case the ratio arms are nearly equal and the end resistances of copper strips also produce the least effect.