Answer
conjugate: $0+4i$
modulus: 4
Work Step by Step
To find the conjugate of a complex number, we reverse the sign of the imaginary part, as follows:
$\overline{-4i}=\overline{0-4i}=0+4i=4i$
Find the modulus using the formula $\sqrt{a^2+b^2}$ for $a+bi$, as follows:
$|0-4i|=\sqrt{0^{2}+(-4)^{2}}=\sqrt{16}=4$
Hence,
conjugate: $0+4i$
modulus: $4$
