Optics

The aim of the following sections is to support teachers especially in their delivery of A level physics, the new GCSE physics courses and vocational courses that contain physics content. It is hoped that students too will benefit directly by using this as a revision resource.

In the main body of the Classroom Space website the emphasis was on using live data from real space missions. Here far more use is made of interactive simulation tools that can be used to explain and explore some of the areas of physics that are used in astronomy, rather than the astronomy itself.

 

Optics

Until the advent of radio astronomy all observations were made in the visible band. As a result basic optics underpins most of astronomy. Even when observations became possible across over wavebands basic optics theory was still used to design almost all observational equipment.

Refraction
This section contains a describes a brief description of how refraction can be used to split light into its component wavelengths. A simulation tool is included to help students understand how a change in the speed of a wave leads to a change in its direction of travel.

Diffraction and Gratings
This section describes both how diffraction can benefit the astronomer (by splitting light up, in a diffraction grating), and how it places a limit on the level of detail that can be obtained from a telescope (the blurring of point like images, i.e. the Airy Disc). Simulation tools are provided for both slit diffraction (simple apertures, double slit and gratings) and circular opennings (the Airy Disc).

Spectroscopy
A picture may tell a thousand words but to an astronomer a spectrum is worth a thousand pictures. This section describes how the analysis of a spectrum (spectroscopy) can be used to determine the chemical composition of a gas. A simulation tool is provided that allows students to practice chemical analysis using spectroscopy.

The Doppler Effect
Chemical analysis is not the only thing that can be determined from a spectrum. The Doppler Effect, commonly heard in speeding ambulances, works for light too. A simulation tool is provided that allows students to practice using the Doppler Effect to make astronomical calculations in a variety of cases.

The Hubble Law
Edwin Hubble's discovery of the expansion of the Universe was arguably one of the greatest scientific results of the 20th century. This section provides a simulation tool that allows students to reproduce Hubble's observations and reach conclussions about the rate of expansion of the Universe

 

Site Administrator: Professor M. A. Barstow. Email: mab@star.le.ac.uk. Page design updated by J. K. Barstow
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