A region has uniform electric and magnetic fields along the positive $x-direction.$ An electron is fired from the origin at an angle $\theta \left(<{90}^{\circ }\right)$ with the x-axis. It will
(i) move along a helical path of increasing pitch
(ii) move along a helical path of decreasing pitch initially
(iii) return to the $yz$ plane at some time
(iv) come to rest momentarily at some position

The peak value $A.C$ is $2\sqrt{2}A.$ It's apparent value will be

Among the following reactions which is impossible

Standard enthalpy and standard entropy changes for the oxidation of ammonia at $298K$ are $-382.64kJmo{l}^{-1}$ and $-145.6j{K}^{-1}mo{l}^{-1}$ respectively. Standard Gibbs energy change for the same reaction at $298K$ is

A current of 2 amp. flows in a long, straight wire of radius $2mm.$ The intensity of magnetic field on the axis of the wire is

The polaroids are placed in the path of unpolarized beam of intensity $I_0$ such that no light is emitted fromthesecond polarid. If a third polaroid whose polarization axis makes an angle $\theta$ with the polarization axis of first polaroid, is placed between these4 polariods then the intensity of light emerging from the last polariod will be

The minimum wavelength of $X$ - rays produced by electrons accelerated by a potential difference of volts is equal to

There exist uniform magnetic and electric fields of manitudes 1T and $1V{m}^{-1}$ respectively, along positive y-axis. A charged particle of mass 1kg and charge 1C is having velocity $1m{s}^{-1}$ along x-axis and is at origin at t=0. Then, the coordinates of the particle at time $\pi s$ will be

A parallel plate capacitor has area of each plate $A$, the separation between the plates is $d.$ It is charged to a potential $V$ and then disconnected from the battery. The amount of work done in the filling the capacitor Completely with a dielectric constant $k$ is.

The value of displacement current at $t=1$ time constant is