Recently Active Modern Physics Questions

A diode made by silicon has a barrier potential of 0.7 volts and current of 20mA passes through the diode when a battery of 3 volts and a resistance of R are in series to it, then the wattage of the resistor is ....... a)46 W ...

*Image* Q52. how to differentiate between (1) and (4) .. they have not stated which direction to take positive axis Q43. yeh kya hai? (i mean i know logic gates.. but what are those dotted and solid lines in input? *Image* ...

Hydrogen atom HA-1 and Hydrogen atom HA-2 are in ground state and in first excited state. A metal plate accepts energies 12.1 eV and 1.9 eV respectively from an Emission spectra.(Work fn=2eV) Find the number of possible lines ...

Two photons having equal wavelength have equal linear momenta but equal linear momenta may not have equal wavelength can anyone explain this statement this is given in hcv i think its wrong see hcv hurdles also ...

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Q. A radioactive nuclide A_{1} with decay constant \lambda _{1} transform into a radioactive nuclide A_{2} with decay constant \lambda _{2} . Assuming that at the initial moment the preparation contained only the radio nuclid ...

If two waves having amplitudes a and b make superposition the resultant amplitude A is given as A = 1 √(a^2 + b^2 + 2ab cosφ) where φ is phase constant. The intensity (I)2 is directly proportional to square of amplitude. ...

Assuming 200 MeV of energy is released for fission of Uranium atom , find the number of fissions per second required to realease 10 kilowatt power. ...

A:though light of a single frequncy (monochromatic) is incident on a metal,the energies of emmited photo elctrons may be diff R:The energy of electrons emmited from inside metal surface is redistributed in collisons with othe ...

The given graphs show the variation of photoelectric current(I) with applied voltage for two different intensities of the incident *Image* ...

Light rays of wavelength 6000 A and of photon intensity 39.6 W/m2 is incident on a metal surface. If only 1% of the photons incident on surface emit photoelectrons, then the number of electrons emmited per second per unit are ...

Draw and explain the output waveform across load resistor if input waveform is shown in fig *Image* ...

1.If the total number of neutrons and protons in a nuclear reaction is conserved, how then is the energy absorbed or evolved in the reaction ? Explain. 2. Compare the radii of two nuclel of mass numbers A1 & A2. ...

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Photoelectric Effect/ Objective I:- Q.2) Two Photons having a) equal wavelengths have equal linear momenta b) equal energies have equal linear momenta c) equal frequencies have equal linear momenta d) equal linear momenta hav ...

Pragraph : A hydrogen octum in third excited state makes a transtion to first excited state and emit photon. This emitted photon is absorbed by He+ ion which was already in seventh excited state. After absorption of photon He ...

Name two factors which determine the choice of a communication channel. Explain the use ofcoaxial cables as a communication channel with the help of its simple diagram. What are the advantages of coaxial cable? ...

1. Light emitting diode a) emits light when forward biased b) Is made from semiconducting compound gallium arsenide c) is made of one of the two basic semi conducting material Si and Ge d) emits light when reverse biased 2. W ...

When a hydrogen atom emits a photon during the transition n = 5 to n = 1, its recoil speed is approximately (a) 4 m/s (b) 800 m/s (c) 3 mm/s (d) 0.1 mm/s ...

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the mean lives of a radioactive substance are 1620yrs for alpha emission and 405yrs for beta emission respectively. find out the time during which three-fourth of the sample will decay if it is decaying both by alpha emission ...

what is spallation ,nuclear reaction and induced radioactivity ?????how to identify these all ????? ...

1.According to moseley, a and b in moseley's law are A)independent of the material B)dependent on the material C)a depends on the material,but b is independent of the material D)none of these 2.Photoelectric effect supports q ...

can any one explain what is lepton number ??? and give any usefull formulae relating to it ?? guys please help .. and guess what it was on ISAT sample paper 2010 !! ...

Just like mass and charge, each particle has a quantity called “Lepton Number”. The table below gives charge and Lepton number of some particles. Like charge, lepton number should be conserved in any physical process. ((p ...

At a given instant there are 25% undecayed radioactive nuclei in a sample. After 10 seconds the number of undecayed nuclei redu ces to 12.5%. Calculate: (i) mean life of the nuclei (ii) the time in which the number of undecay ...

Q1. Light of intensity I falls on a perfectly reflecting surface at an angle θ with the normal to the surface. Find the force exerted by the light on the surface. Q2. A perfectly reflecting solid sphere of radius r is kept i ...

Given a sample pf Radium-2008 having half life of 4 days. Find the probability, nucleus disintegrates after 2 half lives. A. 1 B. 1/2 C. 1.5 D. 3/4 ...

If the potential applied to the tube is doubled and the separation between the between the filament and the target is doubled,the cut-off wave length A. will remain unchanged B. will be doubled. C. will be halved D. will beco ...