The human eye is most sensitive to green light of wavelength 505 nm. Experiments have found tthat when people are kept in a dark room until their eye adapt to the darkness, a single photon of green light will trigger receptor cells in the rods of the retina. The velocity of typical bacterium of mass `9.5xx10^(-12)`g, if it had absorbed all energy of photon ,is nearly

Read the following text and answer the following questions on the basis of the same: Laser: Electromagnetic radiation is a natural phenomenon found in almost all areas of daily life, from radio waves to sunlight to X-rays. Laser radiation - like all light - is also a form of electromagnetic radiation Electromagnetic radiation that has a wavelength between 380 nm and 780 nm is visible to the human eye and is commonly referred to as light. At wavelengths longer than 780 nm, optical radiation is termed infrared (IR) and is invisible to the eye. At wavelengths shorter than 380 nm, optical radiation is termed ultraviolet (UV) and is also invisible to the eye. The term "laser light" refers to a much broader range of the electromagnetic spectrum that just the visible spectrum, anything between 150 nm up to 11000 nm (i.e. from the UV up to the far IR). The term laser is an acronym which stands for "light amplification by stimulated emission of radiation". Einstein explained the stimulated emission. In an atom, electron may move to higher energy level by absorbing a photon. When the electron comes back to the lower energy level it releases the same photon. This is called spontaneous emission. This may also so happen that the excited electron absorbs another photon , releases two photons and returns to the lower energy state. This is known as stimulated emission. Laser emission is therefore a light emission whose energy is used, in lithotripsy, for targeting and ablating the stone inside human body organ. Apart from medical usage, laser is used for optical disk drive, printer, barcode reader etc. Lithotripsy is:

Read the following text and answer the following questions on the basis of the same: Laser: Electromagnetic radiation is a natural phenomenon found in almost all areas of daily life, from radio waves to sunlight to X-rays. Laser radiation - like all light - is also a form of electromagnetic radiation Electromagnetic radiation that has a wavelength between 380 nm and 780 nm is visible to the human eye and is commonly referred to as light. At wavelengths longer than 780 nm, optical radiation is termed infrared (IR) and is invisible to the eye. At wavelengths shorter than 380 nm, optical radiation is termed ultraviolet (UV) and is also invisible to the eye. The term "laser light" refers to a much broader range of the electromagnetic spectrum that just the visible spectrum, anything between 150 nm up to 11000 nm (i.e. from the UV up to the far IR). The term laser is an acronym which stands for "light amplification by stimulated emission of radiation". Einstein explained the stimulated emission. In an atom, electron may move to higher energy level by absorbing a photon. When the electron comes back to the lower energy level it releases the same photon. This is called spontaneous emission. This may also so happen that the excited electron absorbs another photon , releases two photons and returns to the lower energy state. This is known as stimulated emission. Laser emission is therefore a light emission whose energy is used, in lithotripsy, for targeting and ablating the stone inside human body organ. Apart from medical usage, laser is used for optical disk drive, printer, barcode reader etc. What is the full form of LASER?

Read the following text and answer the following questions on the basis of the same: Laser: Electromagnetic radiation is a natural phenomenon found in almost all areas of daily life, from radio waves to sunlight to X-rays. Laser radiation - like all light - is also a form of electromagnetic radiation Electromagnetic radiation that has a wavelength between 380 nm and 780 nm is visible to the human eye and is commonly referred to as light. At wavelengths longer than 780 nm, optical radiation is termed infrared (IR) and is invisible to the eye. At wavelengths shorter than 380 nm, optical radiation is termed ultraviolet (UV) and is also invisible to the eye. The term "laser light" refers to a much broader range of the electromagnetic spectrum that just the visible spectrum, anything between 150 nm up to 11000 nm (i.e. from the UV up to the far IR). The term laser is an acronym which stands for "light amplification by stimulated emission of radiation". Einstein explained the stimulated emission. In an atom, electron may move to higher energy level by absorbing a photon. When the electron comes back to the lower energy level it releases the same photon. This is called spontaneous emission. This may also so happen that the excited electron absorbs another photon , releases two photons and returns to the lower energy state. This is known as stimulated emission. Laser emission is therefore a light emission whose energy is used, in lithotripsy, for targeting and ablating the stone inside human body organ. Apart from medical usage, laser is used for optical disk drive, printer, barcode reader etc. What is the range of amplitude of LASER?

A metal foil is at a certain distance from an isotropic point source that emits energy at the rate P. Let us assume the classical physics to be applicable. The incident light energy will be absorbed continuously and smoothly. The electrons present in the foil soak up the energy incident on them. For simplicity , we can assume that the energy incident on a circular path of the foil with radius 5xx10^(-11) m (about that of a typical atom ) is absorbed by a single electron. The electron absorbs sufficient energy to break through the binding forces and comes out from the foil. By knowing the work function, we can calculate the time taken by an electron to come out i.e., we can find out the time taken by photoelectric emission to start. As you will see in the following questions, the time decay comes out to be large, which is not practically observed. The time lag is very small. Apparently, the electron does not have to soak up energy . It absorbs energy all at once in a single photon electron interaction. if work function of the metal of the foil is 2.2 eV, the time taken by electron to come out is nearly

A metal foil is at a certain distance from an isotropic point source that emits energy at the rate P. Let us assume the classical physics to be applicable. The incident light energy will be absorbed continuously and smoothly. The electrons present in the foil soak up the energy incident on them. For simplicity , we can assume that the energy incident on a circular path of the foil with radius 5xx10^(-11) m (about that of a typical atom ) is absorbed by a single electron. The electron absorbs sufficient energy to break through the binding forces and comes out from the foil. By knowing the work function, we can calculate the time taken by an electron to come out i.e., we can find out the time taken by photoelectric emission to start. As you will see in the following questions, the time decay comes out to be large, which is not practically observed. The time lag is very small. Apparently, the electron does not have to soak up energy . It absorbs energy all at once in a single photon electron interaction. if work function of the metal of the foil is 2.2 eV, the time taken by electron to come out is nearly

In 1924, de-Broglie proposed that every particle possesses wave properties with a wavelength , lambda given by lambda = h/(mv) where m is the mass of the particle, v is its velocity and h is Planck's constant. The de-Broglie prediction was confirmed experimentally when it was found that an electron beam undergoes diffraction , a phenomenon characteristic of waves. The de-Broglie wavelength can be estimated by measuring kinetic energy of an electron accelerating by a potential V as : 1/2 mv^2 = eV "where" 1eV = 1.6 xx 10^(-19) J, h = 6.6 xx 10^(-34) Js . The mass of a photon moving with velocity of light having wavelength same as that of an alpha - particle (mass = 6.6 xx 10^(-27)kg) moving with velocity of 2.5 xx 10^2 ms^(-1) is

A technique called photelectron spectroscopy is used to measure the I.P of atoms. A same is irradiated with U.V light, and electrons are ejected from the valence shell. The kinetic energy of the ejected electrons are measured. Since, the energy of the U.V. photon and the kinetic energy of the ejected electrons are known, we can write hv = I.P. + (1)/(2) m u^(2) Where v is the frequency of the U.V light, and m and u are mass and velocity of the electron respectively. In one experiment the kinetic energy of the ejected electron from potassium is found to be. 5.34 xx 10^(-19) J using U.V. source of wavelength 162 nm. Calculate I.E. of potassium (h = 6.62 xx 10^(-34) J-s, c= 3 xx 10^(8) m " / " s) .