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

when resistance gets very high, the currents that would flow if the bridge was unbalanced become very small, and this may make them hard to detect by the galvanometer. Hence, as resistance increases, your ability to measure it accurately with a bridge decreases.

Can a meter bridge be used to measure very low or very high resistance?

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 the meter bridge is suitable for measuring moderate resistances?

The metre bridge is most sensitive when the resistances of all the four arms of the bridge are of the same order. It is so for moderate resistances only. The metre bridge becomes insensitive for too high or too low resistances.

Why could we not use the Wheatstone bridge to measure the resistance to current flow of an electric heater when it is operating?

For a heater, the resistance keeps changing with time. It increases with increase in temperature. Wheatstone bridge is used only when the resistance remains constant. Thus it can’t be used here.

Why is meter bridge used?

A Meter bridge is used to calculate resistance values with high accuracy. They work on the principle of a balanced Wheatstone bridge.

Can we measure very low resistance by Wheatstone bridge?

Wheatstones’s bridge cannot be used for measurement of very resistances.

How can you increase the sensitivity of Wheatstone bridge?

The sensitivity of the galvanometer itself is decreased if the resistance of the galvanotmeter G is too low. Therefore, we have to increase the sensitivity by increasing n and decreasing m. In the ideal case, if n = ∞ and m = 0.