A cylinder of height $$20$$ $$m$$ is completely filled with water. The velocity of efflux of water (in $$m{s}^{-1}$$) through a small hole on the side wall of the cylinder near its bottom is

The minimum velocity (in $$m{s}^{-1}$$) with which a car driver must traverse a flat curve of radius 150 m and coefficient of friction $$0.6$$ to avoid skidding is

At absolute zero, Si acts as

By increasing the temperature, the specific resistance of a conductor and a semiconductor

The energy band gap is maximum in

The part of a transistor which is most heavily doped to produce large number of majority carriers is

If a spring has time period $$T,$$ and is cut into $$n$$ equal parts, then the time period of each part will be

In a simple harmonic oscillator, at the mean position

A child swinging on a swing in sitting position, stands up, then the time period of the swing will

Electromagnetic waves are transverse in nature is evident by

Which of the following are not electromagnetic waves?

A ball whose kinetic energy E, is projected at an angle of $$45^{\circ }$$ to the horizontal. The kinetic energy of the ball at the highest point of its height will be

A spring of force constant $$800$$ $$N/m$$ has an extension of $$5$$ $$cm.$$ The work done in extending it from $$5$$ $$cm$$ to $$15$$ $$cm$$ is

If a body looses half of its velocity on penetrating $$3$$ $$cm$$ in a wooden block, then how much will it penetrate more before coming to rest?

In a transformer, number of turns in the primary coil are $$140$$ and that in the secondary coil are $$280.$$ If current in primary coil is $$4A,$$ then that in the secondary coil is

The power factor of $$AC$$ circuit having resistance $$(R)$$ and inductance $$(L)$$ connected in series and an angular velocity $$\omega$$ is

At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit \eqalign{ & \left( i \right)\,\,\,\,\,\,\,electrons\,\,\,\,\,\,\,\,\,\,\,\,\left( {ii} \right)\,\,\,\,\,\,\,protons \cr & \left( {iii} \right)\,\,\,H{e^{2 + }}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {iv} \right)\,\,\,\,\,\,\,neutrons \cr} The emission at instant can be

If $$13.6$$ $$eV$$ energy is required to ionize the hydrogen atom, then the energy required to remove an electron from $$n=2$$ is

If $$N_0$$ is the original mass of the substance of half-life period $$t_{1/2}=5$$ years, then the amount of substance left after $$15$$ years is

Which statement is incorrect?