(a) Briefly explain the following terms: (i) emission line spectra; (ii) line absorption spectra. (b) Draw a labeled diagram showing the structure of a simp...
(b) Draw a labeled diagram showing the structure of a simple type of photocell and explain its mode of operation.
(c) State two
(i) reasons to show that x-rays are waves;
(ii) uses of x-rays other than in medicine.
(d) An electron jumps from an energy level of \(-1.6\ \text{eV}\) to one of \(-1.4\ \text{eV}\) in an atom. Calculate the energy and wavelength of the emitted radiation. [ \(h = 6.6 \times 10^{-34}\ \text{Js}\); \(c = 3.00 \times 10^8\ \text{ms}^{-1}\); \(\text{eV} = 1.6 \times 10^{-19}\ \text{J}\) ]
(a)(i) Emission line spectrum: This consists of separate bright lines of definite wavelengths on a dark background. It is produced when excited atoms emit radiation as their electrons fall from higher to lower energy levels.
(ii) Line absorption spectrum: This consists of dark lines on a continuous bright spectrum. It is obtained when continuous light passes through a cool gas, which absorbs particular wavelengths corresponding to its energy transitions.
(b) Simple photocell
A simple vacuum photocell with a photosensitive cathode, collecting anode and external circuit.
When radiation of sufficiently high frequency falls on the photosensitive cathode, photoelectrons are emitted from its surface. The anode is maintained positive relative to the cathode, so it attracts and collects the emitted electrons. The resulting movement of electrons through the external circuit constitutes a photocurrent, which is indicated by the microammeter.
(c)(i) Evidence that X-rays are waves:
They undergo diffraction, for example by crystals.
They undergo interference.
(ii) Uses of X-rays other than in medicine:
Detecting cracks and faults in metal castings and welded joints.
Examining crystal structures.
(d)
For an electron falling from [?25l[?25h\,[?25l[?25h-1.6\,\text{eV}\) to \(-10.4\,\text{eV}\), the energy emitted is
(a)(i) Emission line spectrum: This consists of separate bright lines of definite wavelengths on a dark background. It is produced when excited atoms emit radiation as their electrons fall from higher to lower energy levels.
(ii) Line absorption spectrum: This consists of dark lines on a continuous bright spectrum. It is obtained when continuous light passes through a cool gas, which absorbs particular wavelengths corresponding to its energy transitions.
(b) Simple photocell
A simple vacuum photocell with a photosensitive cathode, collecting anode and external circuit.
When radiation of sufficiently high frequency falls on the photosensitive cathode, photoelectrons are emitted from its surface. The anode is maintained positive relative to the cathode, so it attracts and collects the emitted electrons. The resulting movement of electrons through the external circuit constitutes a photocurrent, which is indicated by the microammeter.
(c)(i) Evidence that X-rays are waves:
They undergo diffraction, for example by crystals.
They undergo interference.
(ii) Uses of X-rays other than in medicine:
Detecting cracks and faults in metal castings and welded joints.
Examining crystal structures.
(d)
For an electron falling from [?25l[?25h\,[?25l[?25h-1.6\,\text{eV}\) to \(-10.4\,\text{eV}\), the energy emitted is
