If $\omega=\frac{z}{z-\frac{1}{3} i}$ and $|\omega|=1$, then $z$ lies on

If $\omega=\frac{z}{z-\frac{1}{3} i}$ and $|\omega|=1$, then $z$ lies on
  1. an ellipse
  2. a circle
  3. a straight line
  4. a parabola.

Solution

As given $w=\frac{z}{z-\frac{1}{3} i} \Rightarrow|w|=\frac{|z|}{\left|z-\frac{1}{3} i\right|}=1 \Rightarrow$ distance of $z$ from origin and point $\left(0, \frac{1}{3}\right)$ is same hence $z$ lies on bisector of the line joining points $(0,0)$ and $(0,1 / 3)$. Hence $z$ lies on a straight line.

Asked in: JEE Main 2005

Practice more Complex Number questions on Aicharya