Invisible visible

1. Cathode ray tube

It fires electrons from a negative electrode through a vacuum towards a fluorescent mineral, thus emitting light. From around 1900. (ID: 4000.1.209)

2. Microscope

Using the mirror as a source of light, the microscope magnifies small specimens with a series of lenses. Possibly from around 1900. Older microscopes have fewer lenses and simpler mechanisms, but the basic principles remains the same. (ID: 3000.43.6)

3. Unknown instrument

Instrument used to display magnetic field lines around an electric conductor. From 1908. (ID: 4000.1.221)

4. Spectrometer

Using a prism, it splits light into its spectrum of different wavelengths. From around 1899-1919. (ID: 3000.63.6)

5. Wehnelt tube

With a fluorescent screen and a deflection electrode. Used to focus and control a beam of electrons. From around 1910. (ID: 4000.1.85)

6. Anode ray tube

Creates beam of positive ions. By applying a voltage, electrons are accelerated in the gas (lithium) creating a visible glow. From around 1900. (ID: 4000.1.89)

7. Cathode ray tube

A beam of electrons in a vacuum strikes the fluorescent screen and emits light. From around 1900. (ID: 4000.1.90)

8. Spectral lamp

The lamp contains a gas. When an electric current is applied, the gas emits spectral lines characteristic for the specific gas atoms in use. (ID: 4000.1.213)

9. Sodium vapor Lamp

Light is produced by applying electricity to sodium atoms. The ionized atoms emits light at a wavelength near 589 nanometer, which appears as a yellow flow. (ID: 4000.1.75)

10. Heat flux sensors

Measures the heat transfer through a surface. It generates an electrical signal proportional to the heat applied to its surface. (ID: 3000.91.123, 4000.25.3, 4000.25.38)

11. X-ray tube

The X-ray tube uses electricity to accelerate electrons in a vacuum tube to prevent electrons from interacting with air molecules. X-rays were discovered in 1895, they are a form of electro magnetic radiation that can penetrate most materials and be used for imaging internal structures of e.g. the human body. (ID: 4000.1.139)

12. Prism

Used for demonstration refraction of light through a prism. The different wavelengths contained in white light is bend at different angles, displaying a spectrum of colours. (ID: 4000.1.121)

13. Oscilloscope

An oscilloscope visualizes the waveform of electronic signals. Modern oscilloscopes uses a digital screen, but this old model uses a rotating mirror deflecting a light beam which displays the waveform on an external screen. From the early 1900s. (ID: 3000.63.38)

14. Bohr’s billiard ball model of the atomic nucleus

In 1936, Niels Bohr explained how atomic nuclei capture neutrons – the basic principle that lead to the discovery of nuclear fission. This model is based on his explanation. It is used with small metal balls representing neutrons. When a ball (a neutron) collides with a nucleus (rolls down the chute), it is likely to hit another ball (another nucleon), which in turn hits another and so on. These repeated collisions will distribute the energy from the added ball evenly between all the balls in the bowl. Therefore, it is unlikely that a ball will roll over the edge (the Coulomb barrier), and thus the ball (neutron) has been "trapped" in the atom. (ID: 4000.1.84)

15. Ocular micrometer

Fits inside the eyepiece of a microscope. To measure microscopic objects by comparing the specimen with a scale engraved on glass inside the micrometer. (ID: 4000.1.33)

16. Crookes tube.

A type of early discharge tube invented by English chemist and physicist William Crookes (1932-1919). A Crookes tube is used to study streams of electrons by making them glow inside a vacuum. (ID: 3000.29.245)