Why meter bridge Cannot be used for measuring very high resistance?

Why meter bridge Cannot be used for measuring very high resistance?

The meter bridge is sensitive when the resistance of all four arms of the bridge are off the same order. If we measure too high resistance and the meter deflection is too small, ie, currents are too low. Similarly. For Too low and you get errors due to the resistance of the wire and the connections.

What is the problem in measuring resistance by Wheatstone bridge?

The resistance of the bridge changes because of the self-heating which generates an error. The thermal emf cause serious trouble in the measurement of low-value resistance. The personal error occurs in the galvanometer by taking the reading or by finding the null point.

Can we measure very low resistance by Wheatstone bridge?

Variations on the Wheatstone bridge can be used to measure capacitance, inductance, impedance and other quantities, such as the amount of combustible gases in a sample, with an explosimeter. The Kelvin bridge was specially adapted from the Wheatstone bridge for measuring very low resistances.

Can you measure very high resistance using meter bridge?

So, Can you find very high resistance accurately with the help of a Metre bridge? No, the metre bridge becomes insensitive for very high and very low resistance. If too high resistance is measured then the deflection of the metre bridge will be very small. This means that the currents are also too low.

Why is meter bridge not preferred?

The metre bridge becomes insensitive for too high or too low resistances. Moreover, while measuring low resistances, the resistances of the copper strips and the connecting wires become comparable to the unknown low resistance and hence cannot be neglected.

Can Wheatstone bridge measure high resistance?

As such it is suitable also for high value resistors. What is required though is a sensitive volt/current meter in the middle. A galvanometer is not that sensitive so a Wheatstone Bridge using a galvanometer is limited to resistor values up to around maybe 1 Mega ohm.

Can we find very high or very low resistance accurately with a Metre bridge?

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.

Why is a Wheatstone bridge not suitable for measuring high and low?

Originally Answered: Why is the Wheatstone bridge method not suitable for measurements that are very low and have very high resistance? Low Resistance: Wheatstone Bridge can not be used to measure low resistance because then the wire resistance and lead resistance come into the picture and affect the result.

What happens when you change resistor on Wheatstone bridge?

Wheatstone Bridge Circuit. By replacing R4 above with a resistance of known or unknown value in the sensing arm of the Wheatstone bridge corresponding to RX and adjusting the opposing resistor, R3 to “balance” the bridge network, will result in a zero voltage output.

What are the arms of a Wheatstone bridge circuit?

A Wheatstone bridge circuit consists of four arms of which two arms consists of known resistances while the other two arms consist of an unknown resistance and a variable resistance. The circuit also consists of a galvanometer and an electromotive force source.

How does null deflection work on a 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 circuit. When is the Wheatstone Bridge balanced? A Wheatstone bridge is said to be in a balanced condition when no current flows through the galvanometer.