Find the modulus of each of the following:

Given: $z=3 i$

The above equation can be re – written as

$z=0+3 i$

Now, we have to find the modulus of (0 + 3i)

So, $|z|=|0+3 i|=\sqrt{(0)^{2}+(3)^{2}}=\sqrt{9}=3$

Hence, the modulus of (3i) is 3