When is a Wheatstone bridge said to be balanced?

What is a Wheatstone bridge ?

In a Wheatstone's network, P=2Omega, Q=2Omega, R=2Omega and S=3Omega . The resistance with which S is to be shunted in order that the bridge may be balanced is

On sending the current in the Wheatstone's network, the network is said to be balanced, if

In a Wheatstone's bridge, three resistances P,Q and R connected in the three arms and the fourth arm is formed by two resistances S_1 and S_2 connected in parallel. The condition for the bridge to be balanced will be

Explain the use of Wheatstone's meter bridge to determine an unknown resistance.

What are the advantages of the null-point method in a Wheatstone bridge ? What additional measurements would be required to calculate R -unknown by any other method ?

When is acceleration said to be positive?

When is a transistor said to be in active state ?