When $$p$$-$$n$$ junction diode is forward biased then

For a transistor amplifier in common emitter configuration for load impedance of $$1k\Omega$$ $$(h_{fe}=50$$ and $$h_{oe}=25)$$ the current gain is

The manifestation of band structure in solids is due to

When $$npn$$ transistor is used as an amplifer

In forced oscillation of a particle the amplitude is maximum for a frequency $${\omega }_1$$ of the force while the energy is maximum for a frequency $${\omega }_2$$ of the force; then

The bob of a simple pendulum executes simple harmonic motion in water with a period $$t,$$ while the period of oscillation of the bob is $$t_0$$ in air. Neglecting frictional force of water and given that the density of the bob is $$\left(4/3\right)\times 1000kg/m^3.$$ What relationship between $$t$$ and $$t_0$$ is true

The total energy of particle, executing simple harmonic motion is

A particle at the end of a spring executes $$S.H.M$$ with a period $$t_1$$. While the corresponding period for another spring is $$t_2$$. If the period of oscillation with the two springs in series is $$T$$ then

A particle of mass $$m$$ is attached to a spring (of spring constant $$k$$) and has a natural angular frequency $${\omega }_0.$$ An external force $$F(t)$$ proportional to $$\cos \omega t\left(\omega \ne {\omega }_0\right)$$ is applied to the oscillator. The time displacement of the oscillator will be proportional to

An electromagnetic wave of frequency $$v=3.0$$ $$MHz$$ passes from vacuum into a dielectric medium with permittivity $$\in =\mathrm{4.0.}$$ Then

A radiation of energy $$E$$ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particles takes place in a plane. It follows that

A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement $$x$$ is proportional to

A uniform chain of length $$2$$ $$m$$ is kept on a table such that a length of $$60$$ $$cm$$ hangs freely from the edge of the table. The total mass of the chain is $$4$$ $$kg.$$ What is the work done in pulling the entire chain on the table?

A force $$\overrightarrow{F}=\left(5\overrightarrow{i}+3\overrightarrow{j}+2\overrightarrow{k}\right)N$$ is applied over a particle which displaces it from its origin to the point $$\overrightarrow{r}=\left(2\overrightarrow{i}-\overrightarrow{j}\right)m.$$ The work done on the particle in joules is

A body of mass $${}^{\prime }{m}^{\prime },$$ acceleration uniformly from rest to $${}^{\prime }{v_1}^{\prime }$$ in time $$T$$. The instantaneous power delivered to the body as a function of time is given by

In an $$LCR$$ series $$a.c.$$ circuit, the voltage across each of the components, $$L,C$$ and $$R$$ is $$50V$$. The voltage across the $$L.C$$ combination will be :

Alternating current can not be measured by $$D.C.$$ ammeter because

In a $$LCR$$ circuit capacitance is changed from $$C$$ to $$2$$ $$C$$. For the resonant frequency to remain unchaged, the inductance should be changed from $$L$$ to

The binding energy per nucleon of deuteron $$\left({}_1^{2}H\right)$$ and helium nucleus $$\left({}_2^{4}He\right)$$ is $$1.1$$ $$MeV$$ and $$7$$ $$MeV$$ respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is