In an $$AC$$ generator, a coil with $$N$$ turns, all of the same area $$A$$ and total resistance $$R,$$ rotates with frequency $$\omega$$ in a magnetic field $$B.$$ The maximum value of $$emf$$ generated in the coil is

When $${}_{3}L{i}^7$$ nuclei are bombarded by protons, and the resultant nuclei are $${}_{4}B{e}^8$$, the emitted particles will be

If the binding energy per nucleon in $${}_3^{7}Li$$ and $${}_2^{4}He$$ nuclei are $$5.60$$ $$MeV$$ and $$7.06$$ $$MeV$$ respectively, then in the reaction $p + {}_3^7Li \to 2\,{}_2^4He$ energy of proton must be

The $${}^{\prime }ra{d}^{\prime }$$ is the correct unit used to report the measurement of

An alpha nucleus of energy {1 \over 2}m{v^2} bombards a heavy nuclear target of charge $$Ze$$. Then the distance of closest approach for the alpha nucleus will be proportional to

The energy spectrum of $$\beta$$-particles [ number $$N(E)$$ as a function of $$\beta$$-energy $$E$$ ] emitted from a radioactive source is

The work of $$146$$ $$kJ$$ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by $$7^{\circ }C.$$ The gas is $$\left(R=8.3Jmo{l}^{-1}{K}^{-1}\right)$$

Assuming the Sun to be a spherical body of radius $$R$$ at a temperature of $$TK$$, evaluate the total radiant powered incident of Earth at a distance $$r$$ from the Sun Where r0 is the radius of the Earth and $$\sigma$$ is Stefan's constant.

Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature $$T_0,$$ while Box contains one mole of helium at temperature \left( {{7 \over 3}} \right){T_0}. The boxes are then put into thermal contact with each other, and heat flows between them until the gases reach a common final temperature (ignore the heat capacity of boxes). Then, the final temperature of the gases, $$T_f$$ in terms of $$T_0$$ is

An electric dipole is placed at an angle of $$30^{\circ }$$ to a non-uniform electric field. The dipole will experience

Two spherical conductors $$A$$ and $$B$$ of radii $$1$$ $$mm$$ and $$2$$ $$mm$$ are separated by a distance of $$5$$ $$cm$$ and are uniformly charged. If the spheres are connected by a conducting wire then in equilibrium condition, the ratio of the magnitude of the electric fields at the surfaces of spheres $$A$$ and $$B$$ is

Two insulating plates are both uniformly charged in such a way that the potential difference between them is $$V_2-V_1=20V.$$ (i.e., plate $$2$$ is at a higher potential). The plates are separated by $$d=0.1$$ $$m$$ and can be treated as infinitely large. An electron is released from rest on the inner surface of plate $$1.$$ What is its speed when it hits plate $$2$$? $$\left(e=1.6\times {10}^{-19}C,m_e=9.11\times {10}^{-31}kg\right)$$

A particle located at x = 0 at time t = 0, starts moving along the positive x-direction with a velocity 'v' that varies as $$v=\alpha \sqrt{x}$$. The displacement of the particle varies with time as

The threshold frequency for a metallic surface corresponds to an energy of $$6.2$$ $$eV$$ and the stopping potential for a radiation incident on this surface is $$5V.$$ The incident radiation lies in

The time taken by a photoelectron to come out after the photon strikes is approximately

The anode voltage of a photocell is kept fixed. The wavelength $$\lambda$$ of the light falling on the cathode is gradually changed. The plate current $$\mathrm{I}$$ of the photocell varies as follows

Needles $$N_1$$, $$N_2$$ and $$N_3$$ are made of ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will

A whistle producing sound waves of frequencies $$9500$$ $$Hz$$ and above is approaching a stationary person with speed $$v$$ $$m{s}^{-1}.$$ The velocity of sound in air is $$300m{s}^{-1}.$$ If the person can hear frequencies upto a maximum of $$10,000$$ $$HZ,$$ the maximum value of $$v$$ upto which he can hear whistle is

A string is stretched between fixed points separated by $$75.0$$ $$cm.$$ It is observed to have resonant frequencies of $$420$$ $$Hz$$ and $$315$$ $$Hz$$. There are no other resonant frequencies between these two. Then, the lowest resonant frequency for this string is

A long solenoid has $$200$$ turns per $$cm$$ and carries a current $$i.$$ The magnetic field at its center is $$6.28\times 10^{-2}Weber/m^2.$$ Another long solenoid has $$100$$ turns per $$cm$$ and it carries a current {i \over 3}. The value of the magnetic field at its center is