NEET 2018

A block of mass m is placed on a smooth inclined wedge ABC of inclination $$\theta$$ as shown in the figure. The wedge is given an acceleration ‘a towards the right. The relation between a and $$\theta$$ for the block to remain stationary on the wedge is

An em waveis propagating in a medium with a velocity $$\overrightarrow{V}=V\hat{i}$$ The instantaneous oscillating electric field of this em wave is along +y axis.Then the direction of oscillating magnetic field of the em wavewill be along

The refractive index of the material of a prism is $$\sqrt{2}$$ and the angle of the prism is $$30^\circ$$.one of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface)if its angle of incidence on the prism is

The magnetic potential energy stored.in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductoris:of inductance

An object is placed at a distance of 40 cm from a concave mirror of.focal length 15 cm.If the object is displaced through a distance of 20 cm towards the mirror, the displacementofthe image will be

The ratio of kinetic energy to the total energy of an electron in a Bohrorbit of the hydrogen atom, is

An electron of mass m with an initial velocity $$\overrightarrow{V}=V_{0} \hat{i} (V_{0}>0)$$ enters an electric field $$\overrightarrow{E}=-E_{0} \hat{i}$$ $$(E_{0}=constant >0)$$ at t=0. If $$\lambda_{0}$$ is its de-Broglie wavelength initially, then its de-Broglie wavelength at timet is

when the light of frequency 2 $$\nu_{0}$$ ( where $$\nu_{0}$$ is threshhold frequency), is incident on a metal plate ,the maximum velocity of electrons emitted is $$v_{1}$$.when the frequency of the incident radiation is increased to 5 $$\nu_{0}$$, the maximum velocity of electrons emitted from the same plate is $$V_{2}$$.The ratio of $$V_{1}$$ to $$V_{2}$$ is

For a radioactive material, half-life is 10 minutes. If initially there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is

The volume (V) of a monatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state A to state B, is