Which of the following alkenes does $NOT$ exhibit $cis-trans$ isomerism?

Radius of gyration of a body depends on

The currents $i_1$ and $i_2$ through the resistors $R_1 = 10\,\Omega$ and $R_2 = 30\,\Omega$ in the circuit diagram with $E_1 = 3\,V$,$E_2 = 3\,V$,and $E_3 = 2\,V$ are respectively:

The number of electrons in the valence shell of the central atom of a molecule is $8$. The molecule is

If $C, R, L$ and $I$ denote capacity,resistance,inductance and electric current respectively,the quantities having the same dimensions of time are :
$(1)$ $C R$
$(2)$ $\frac{L}{R}$
$(3)$ $\sqrt{L C}$
$(4)$ $L I^2$

Current $I$ is flowing in a conductor shaped as shown in the figure. The radius of the curved part is $r$ and the length of the straight portions is very large. The value of the magnetic field at the centre $O$ will be