(a) (i) Define atomic spectra.
(ii) Differentiate between emission spectra and absorption spectra.
The diagram above illustrates an electron transition from energy level n = 3 to n = 1. Calculate the:
(ii) wavelength of the photon [h = 6.6 x 10\(^{-34}\)J s, c = 3.0 x 10\(^8\) ms\(^{-1}\); 1 ev = 1.6 x 10\(^{-19}\) J]
c)(i)Differentiate between soft x-rays and hard x-rays
(ii) Draw the circuit symbol for a p-n junction diode.
a)
(i) Atomic spectra refers to the range of electromagnetic radiation emitted or absorbed by atoms. It is a characteristic of the arrangement of electrons in atoms and the energy changes that occur within them.
(ii) Emission spectra refer to the range of electromagnetic radiation emitted by an atom when it transitions from a higher energy level to a lower energy level. Absorption spectra, on the other hand, refer to the range of electromagnetic radiation absorbed by an atom when it transitions from a lower energy level to a higher energy level.
b)
(i) The energy of the photon can be calculated using the equation E = hf, where E is energy, h is Planck's constant, and f is frequency. Thus, E = (6.6 x 10^-34 J s) x (3.0 x 10^8 Hz) / (3 - 1) = 4.4 x 10^-19 J.
(ii) The frequency of the photon is given by f = c / λ, where c is the speed of light and λ is the wavelength. Thus, f = (3.0 x 10^8 m/s) / (6.56 x 10^-7 m) = 4.58 x 10^14 Hz.
(iii) The wavelength of the photon can be calculated using the equation λ = c / f. Thus, λ = (3.0 x 10^8 m/s) / (4.58 x 10^14 Hz) = 6.56 x 10^-7 m.
c)
(i) Soft x-rays have lower energy and longer wavelength than hard x-rays. They are more easily absorbed by matter and are used in medical imaging. Hard x-rays, on the other hand, have higher energy and shorter wavelength and can penetrate denser materials, such as bone and metal.
(ii) The circuit symbol for a p-n junction diode is a triangle with a line at the base. The triangle represents the p-type material, and the line represents the n-type material.
(iii) Doping a semiconductor material involves intentionally adding impurities to change its electrical properties. This is done to create p-type or n-type semiconductors, which have different electron arrangements and conductivities. P-type semiconductors have an excess of holes and are created by doping with elements that have fewer valence electrons, while n-type semiconductors have an excess of electrons and are created by doping with elements that have more valence electrons.
