Explanation
According to Einstein’s photoelectric equation.
Photoelectric effect demonstrates the particle nature of light. Number of emitted photoelectrons depends upon the intensity of light.
X-rays lie in electromagnetic spectrum.
The atomic number (number of electrons or protons) remains same in isotope. Isotope of an element can be separated on account of their different atomic weight by using mass spectrograph.
The specific charge (e/m) of the positive rays is not universal constant because these rays may consist of ions of different elements.
Less work function means less energy is required for ejecting out the electrons.
If electron is moving parallel to the magnetic field, then the electron is not deflected i. e., if electron is nor deflected we cannot be sure that there is no magnetic field in that region.
At normal pressure positive ions and electrons liberated by ionisation of gas atoms, due to cosmic rays arc very small in number and they collide constantly with the gas atoms which are present in large numbers, kind hence arc unable to move a long distance under the electric field and soon get recombined i. e., flow of ions in the gas does not take place.
Light is produced in gases in the process of electric discharge at low pressure. When accelerated electrons collide with atoms of the gas, atoms get excited. The excited atoms return to their normal state and in this process light radiations are emitted.
If electric field is used for detecting the electron beam, then very high voltage will have to be applied or very long tube will have to be taken.
Specific charge of a positive ion corresponding to one gas is fixed hut it is different for different gases.
Only the photoelectrons emitted from the surface of the metal have maximum kinetic energy. Those emitted from inside the metal loses part of their energy in collision with the other atoms inside the metal.
On increasing the intensity of incident light, the current in photoelectric cell will increase. The energy of the photons (hv) will, however not increase with increase in intensity, and hence the kinetic energy of the emitted electrons will not increase.
The photoemissive cell may be evacuated contain an inert gas at low pressure. An inert gas in the cell gives greater current but causes a time lag in the response of the cell to very rapid changes of radiation which may make it unsuitable for some purpose.
Wavelength of X-rays is very small (≈ Å). Hence they arc not diffracted by means of ordinary grating. X- rays following the Bragg’s law.
The penetrating power of X-rays depends upon the voltage applied across the tube producing X-rays. X-rays can pass through matter of lighter elements such as flesh (which is composed of oxygen, hydrogen and carbon) but cannot pass through substances made of heavier elements like bones (which are made of phosphorus and calcium).
Intensity of X-rays (I) is proportional to the filament current and also to the square of the voltage. It is well known the that intensity of X-rays depends on the number of photons emitted per second from target.
Soft and hard X-rays differ only in frequency. But both types of X-rays travel with speed of light.
Higher the wavelength of X-rays, lesser is the frequency and penetration power.
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