Question

Can you find very high resistance accurately with the help of a Metre bridge?

Answer 1

Hint : A Wheatstone bridge is an electrical circuit that balances two legs of a bridge circuit, one of which includes the unknown component, to measure an unknown electrical resistance. The circuit's main advantage is its capacity to produce highly exact readings (in contrast with something like a simple voltage divider). It works in the same way as the original potentiometer.

Complete Step By Step Answer:
The Wheatstone bridge (Metre Bridge) technique is ineffective for measuring extremely low and extremely high resistance.
Because, in order to assure the bridge's sensitivity, all other resistances utilised should be either extremely low or very high in value.
This also necessitates a galvanometer with either low or extremely high resistance, which introduces inaccuracy into the findings.
If the resistance is too high, the metre deflection is too little, implying that the currents are too low.
When the resistance of the cable and connections is too low, mistakes occur.
The metre bridge is a device that operates on the same concept as Wheatstone's bridge. To find the unknown resistance, a metre bridge is employed. When the resistance of all four bridge arms is of the same order, the metre bridge is sensitive.
So, can you use a Metre bridge to precisely detect really high resistance? No, for very high and very low resistance, the metre bridge becomes insensitive. The deflection of the metre bridge will be extremely little if the resistance is too great. This also indicates that the currents are too low.
When the resistances of all four arms of the metre bridge are of the same order, the metre bridge is most responsive. This is only true for modest resistances. For too high or too low resistances, the metre bridge becomes insensitive. Furthermore, when measuring low resistances, the resistances of the copper strips and connecting wires are equivalent to the unknown low resistance and so cannot be ignored.

Note :
The Wheatstone bridge exemplifies the notion of a difference measurement, which may be quite precise. An explosimeter can be used to measure capacitance, inductance, impedance, and other quantities, such as the quantity of flammable gases in a sample, using variations on the Wheatstone bridge. For measuring very low resistances, the Kelvin bridge was modified from the Wheatstone bridge. In many situations, the importance of measuring the unknown resistance is linked to determining the influence of some physical phenomena (such as force, temperature, pressure, and so on), allowing the Wheatstone bridge to be used to indirectly measure those factors.