For the complex number $z= \frac{a+jb}{a-jb},$ where $a>0$ and $b>0.$
Which of the following statement(s) is/are true?
- The phase is $2 \; \tan^{-1}\frac{b}{a}$
- The phase is $ \; \tan^{-1}\frac{2b}{a}$
- The magnitude is $1$
- The magnitude is $\sqrt{\frac{a^{2}+b^{2}}{a^{2}-b^{2}}}$