A particle of charge $q$ and mass $m$ is moving along the $x-$ axis with a velocity $v,$ and enters a region of electric field $E$ and magnetic field $B$ as shown in figures below. For which figure the net force on the charge may be zero :-

A point source of electromagnetic radiation has an average power output of $800\,W$ . The maximum value of electric field at a distance $3.5\,m$ from the source will be.....$V/m$

An antenna is placed in a dielectric medium of dielectric constant $6.25$. If the maximum size of that antenna is $5.0\, mm$. it can radiate a signal of minimum frequency of $GHz .$

(Given $\mu_{ r }=1$ for dielectric medium)

If $\overrightarrow E $ and $\overrightarrow B $ are the electric and magnetic field vectors of E.M. waves then the direction of propagation of E.M. wave is along the direction of

Suppose that intensity of a laser is $\left(\frac{315}{\pi}\right)\, W / m ^{2} .$ The $rms$ electric field, in units of $V / m$ associated with this source is close to the nearest integer is $\left(\epsilon_{0}=8.86 \times 10^{-12} C ^{2} Nm ^{-2} ; c =3 \times 10^{8} ms ^{-1}\right)$

A plane electromagnetic wave with frequency of $30 {MHz}$ travels in free space. At particular point in space and time, electric field is $6 {V} / {m}$. The magnetic field at this point will be ${x} \times 10^{-8} {T}$. The value of ${x}$ is ..... .