1.1. The lowest energy levels of a hydrogen atom are represented in Figure 1. The diagram is not to scale.

Use Figure 1 to identify the transition which produces a photon with frequency of 2.93 × 10¹⁵ Hz.

1.2. An excited hydrogen atom can emit photons of certain discrete frequencies in various regions of the electromagnetic spectrum. Three possible transitions are shown in Figure 2.

Identify the transitions in Figure 2 which produce a photon in the following region of the electromagnetic spectrum: 

• Visible

• Ultraviolet

• Infrared

1.3. Explain why the emitted photons in part (b) have certain discrete frequencies. 

1.4. An electron in the hydrogen atom is ionised by a photon of light with frequency 3.7 × 10¹⁵ Hz.

Calculate the kinetic energy of the ionised electron.