Question

What is null voltage?

Answer 1

Null voltage:

1. Null voltage means zero voltage. Null is a fixed point in a field as shown in figure :
2. 
3. When there is no current measure through the device it shows zero deflection.
4. The field quantity is zero due to the total cancellation of two or more quantities.
5. Some instruments need zero voltage like the Wheatstone bridge which is achieved through null deflection.