Between $cis$ and $trans$ isomers,which has a higher dipole moment? Explain with an example.

(N/A) $CH_3-CH=CH-CH_3$ (but-$2$-ene) exhibits geometrical isomerism with two isomers:
$(i)$ $cis$-but-$2$-ene
$(ii)$ $trans$-but-$2$-ene
Generally,the dipole moment $(\mu)$ of the $cis$-isomer is greater than that of the $trans$-isomer.
In $trans$-but-$2$-ene,the two $-CH_3$ groups are on opposite sides of the double bond. Consequently,the bond dipoles of the $C-CH_3$ bonds are equal and opposite,cancelling each other out,which makes the $trans$-isomer non-polar $(\mu = 0)$.
In $cis$-but-$2$-ene,the two $-CH_3$ groups are on the same side of the double bond. The bond dipoles of the $C-CH_3$ bonds reinforce each other,resulting in a net dipole moment $(\mu \approx 0.33 \ D)$. Therefore,the $cis$-isomer is polar while the $trans$-isomer is non-polar.