Perminvar alloy having constant permeability is an alloy of

Answer: Option A

The correct answer is Option A: Nickel, copper and iron

Here's why:

Perminvar is a special type of alloy known for its exceptionally constant magnetic permeability over a wide range of magnetic field strengths.

This unique property is achieved through a specific combination of elements.

Key Takeaway: Perminvar alloys are primarily composed of Nickel (Ni), Copper (Cu), and Iron (Fe).

The other options contain different elements (like zinc, antimony, and bismuth) that are not used in the standard composition of Perminvar.