# Turning points in Physics in a Box

Five key turning points in Physics are illustrated in our Lab in a Box scheme. Schools and Colleges can borrow five experiments to illustrate key discoveries in the study of Physics.

Supporting the A level Option “ Turning Points in Physics”

## 1. Electron Diffraction

The wave-particle duality concept is central to understanding quantum physics.The A level Specification introduces the DeBroglie equation and this experiment uses it along with the diffraction equation to find the spacing between carbon atoms in graphite.

## 2. Measuring the specific charge of an electron (or the e/m ratio)

The measuring the e/m ratio of an electron was very important so Physics at the beginning of the 1900s could gain a better understanding of this newly discovered particle. The experiment uses equations from circular motion and forces on electrons in magnetic fields which is part of the A2 physics syllabus as well as being in the Turning Points in Physics Module. The experiment needs a fully darkened space.

## 3. Microwave Interferometer

One of the most important turning points in Physics was the Mitchelson Morely Experiment which implied that light did not need a medium to propagate The microwave interferometer instructs students on the basics and the BOX has support material which discusses the famous experiment. Also in the box is a double slit apparatus which can be used to find the wavelength of the microwaves using Young’s Slits equation.

## 4. Millikan’s Oil Drop Experiment

It was always important to measure the charge of an electron. Millikan’s ingenious experiment is available here for students to do themselves. They must find a drop, then find a voltage which will cause it to hover. The students must then measure the terminal velocity when it falls freely.

## 5. Planck's Constant

Planck’s Constant must be one of the most used in modern physics. This experiment uses the photoelectric effect and Einstein's equation to measure the constant h. The box also contains a class set of LED boxes where the constant can bemeasured using a voltmeter and an ammeter using the equation E = hf.