Energy levels in atoms and line spectra

State what the term photon means.

Feb/March 2017

Use band theory to explain why the resistance of an intrinsic semiconductor falls as temperature rises, unlike the resistance of a copper wire.

Feb/March 2017

Fig. 11.1 shows some electron energy bands in a solid. The width of the forbidden band, together with the number density of charge carriers in each band, depends on the type of solid. Use band theory to explain why

Feb/March 2018

Explain the meaning of a photon.

May/June 2012

Explain what the term photon means.

May/June 2012

Atomic hydrogen gives an emission spectrum made up of several discrete wavelengths. Explain how this observation shows that atoms contain discrete electron energy levels.

May/June 2013

Fig. 12.1 shows some of the electron energy bands present in a solid.

May/June 2016

Some of the electron energy bands in a solid are shown in Fig. 12.1.

May/June 2016

A beam of light is made up of a continuous spread of wavelengths between $420\,\text{nm}$ and $740\,\text{nm}$. It then passes through a cloud of cool gas, as shown in Fig. 11.1.

May/June 2017

The light beam contains a continuous spread of wavelengths from $420\,\text{nm}$ to $740\,\text{nm}$. It then travels through a cloud of cool gas, as illustrated in Fig. 11.1.

May/June 2017

As shown in Fig. 10.1, white light travels through a cloud of cool gas at low pressure. After the gas has been crossed, its continuous spectrum is observed to have several darker lines.

May/June 2020

White light is sent through a cloud of cool low-pressure gas, as shown in Fig. 10.1. In the light that emerges from the gas, the continuous spectrum is seen to contain several darker lines. Use the idea of discrete electron energy levels to explain why these darker lines appear.

May/June 2020

Fig. 8.1 presents the four lowest energy levels of an electron in an isolated atom. Fig. 8.2 presents the emission-spectrum lines of the atom for the electron transitions from $n = 3$ to $n = 1$ and from $n = 4$ to $n = 1$.

May/June 2023

Fig. 8.1 shows a section of the visible emission spectrum produced by hydrogen gas in a star within a galaxy that is far away. That galaxy is receding from Earth at a speed of $6.2 \times 10^{6}\,\text{m s}^{-1}$.

May/June 2024

State an effect that gives evidence for the wave nature of a particle.

Oct/Nov 2010

Explain how hydrogen’s line spectrum gives evidence that atoms contain discrete electron energy levels.

Oct/Nov 2011

Explain how the hydrogen line spectrum serves as evidence for discrete electron energy levels in atoms.

Oct/Nov 2011

White light falls onto a cloud of cool hydrogen gas, as shown in Fig. 8.1. The spectrum of the light leaving the gas cloud is observed to include several dark lines.

Oct/Nov 2014

White light falls on a cloud of cool hydrogen gas, as shown in Fig. 8.1. The spectrum of the light that leaves the gas cloud is observed to include several dark lines.

Oct/Nov 2014

Figure 11.1 shows several of the electron energy bands present in a solid. The width of the forbidden band and the number of charge carriers in each band depend on the nature of the solid.

Oct/Nov 2016

Fig. 10.1 shows some of the electron energy bands in a semiconductor at absolute zero temperature.

Oct/Nov 2018

Fig. 10.1 shows some of the electron energy bands in a semiconductor material at absolute zero temperature.

Oct/Nov 2018

Fig. 10.1 depicts the higher electron energy bands in an intrinsic semiconductor material.

Oct/Nov 2019

Fig. 8.1 displays the three lines with the lowest frequencies in the section of the hydrogen emission spectrum that corresponds to electron transitions down to the ground state (level $n = 1$). The figures give the frequencies, in $10^{15}\,\text{Hz}$, for the spectral lines.

Oct/Nov 2025