Mathematics
What is Imaginary numbers?
Imaginary numbers are numbers based on the square root of -1, written as i. Since no real number squared gives a negative, mathematicians invented i to solve such equations — and it turns out to be hugely useful in engineering and physics.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains imaginary numbers.
Key things to understand
- 1They're built on i, defined as the square root of -1.
- 2No ordinary (real) number squared can give a negative result.
- 3Combined with real numbers they form 'complex numbers'.
- 4They're essential in electronics, signal processing, and physics.
Frequently asked questions
- What is an imaginary number?
- A multiple of i, where i is defined as the square root of -1 — something no real number can be.
- Are imaginary numbers actually useful?
- Yes — they're vital in electrical engineering, signal processing, quantum physics, and more.
- What is a complex number?
- A number with a real part and an imaginary part, like 3 + 2i, combining both kinds of number.