The magnetic field vector of an electromagnetic wave is given by $B=B_0\frac{\hat{\mathrm{i}}+\hat{\mathrm{j}}}{\sqrt{2}}\cos \left(kz-\omega t\right)$ where $\hat{\mathrm{i}}, \hat{\mathrm{j}}$ represents unit vector along $x$ and $y$-axis respectively. At $t=0 \mathrm{s},$ two electric charges $q_1$ of $4\pi$ coulomb and $q_2$ of $2\pi$ coulomb located at $\left(0, 0, \frac{\pi }{k}\right)$ and $\left(0, 0, \frac{3\pi }{k}\right),$ respectively, have the same velocity of $0.5\mathrm{c}\hat{\mathrm{i}},$ (where $c$ is the velocity of light ). The ratio of the force acting on charge $q_1$ to $q_2$ is :

Following plots show Magnetization $\left(M\right)$ vs Magnetising field $\left(H\right)$ and Magnetic susceptibility $\left(\mathrm{\chi }\right)$ vs Temperature $\left(T\right)$ graph :

Which of the following combination will be represented by a diamagnetic material?

There are two infinitely long straight current-carrying conductors and they are held at right angles to each other so that their common ends meet at the origin as shown in the figure given below. The ratio of current in both conductors is $1:1$. The magnetic field at point $P$ is$\_\_\_\_\_\_\_\_\_.$

Statement I : The ferromagnetic property depends on temperature. At high temperature, ferromagnet becomes paramagnet.

Statement II : At high temperature, the domain wall area of a ferromagnetic substance increases. In the light of the above statements, choose the most appropriate answer from the options given below: