The core material in an LVDT must be ferromagnetic to ensure efficient coupling between the coils.
Among the options:
- Nickel-iron is an ideal material for the core of an LVDT because of its magnetic properties that ensure a strong and stable inductive coupling.
- Air does not have the required magnetic properties to support the inductive coupling, making it unsuitable.
- Rubber is a non-magnetic material and does not contribute to the inductive coupling in an LVDT.
- Platinum is not typically used as the core material in LVDTs due to its cost and lack of suitable magnetic properties for this application.
Therefore, the correct answer is Nickel-iron.
An op-amp has an offset voltage of 1 mV and is ideal in all other respects. If this op-amp is used in the circuit shown in figure below, the output voltage will be (select the nearest value):