It’s a crowd-pleasing party trick: Cut a grape in half, pop it in the microwave, hit “start” then sit back and watch the dazzling “grape balls of fire.” Now a team of Canadian scientists has figured out how grapes generate plasma in your kitchen.
Measuring tiny volumes with precision and accuracy requires a micropipet. In the biology lab, micropipets are used for preparing and loading DNA samples, microscale experiments and the preparation of many types of samples. These applications rely on good technique to reduce error. This guide explains how to choose the proper micropipet for the application and techniques to help ensure that measurements are accurate and precise.
Hans Christian Oersted (1777–1851), a Danish physicist, was performing an experiment in 1820 when he noticed that whenever an electric current from a battery was switched on or off, a nearby compass needle was deflected. Through additional experiments, Oersted was able to demonstrate the link between electricity and magnetism. The following year, English scientist Michael Faraday (1791–1867) created a device that produced “electromagnetic rotation.” This device is known as a homopolar motor since the motor requires no commutator to reverse the current.
A motor converts electrical energy to mechanical energy. The simple motor in this activity changes the electrical energy output by the battery to mechanical energy as the copper wire is set into rotational motion. Any current-carrying wire produces an associated magnetic field. The electrons in the wire are subjected to a magnetic field and experience a force—referred to as the Lorentz force—that is perpendicular to both the magnetic field and the direction of movement. At some point along the length of the wire, the electrical current is not parallel to the magnetic field. The resulting Lorentz force is tangential and induces a torque on the copper wire. This torque causes the copper wire to spin.
How do astronauts survive the deadly radiation of deep space? NASA is still figuring out how to protect astronauts from cosmic radiation — like plastic shielding and magnetic deflectors. Continue reading
The bottom of the cereal box is a disappointing place. But at least now you know why. Where do you see the Brazil Nut Effect around you? Continue reading
When charge moves, we call it electric current, but the word current is usually reserved for things like water flows. Does electric current really work like that? Electrons are quantum particles, so we have to be careful.
Our “Five-Minute Safety Equipment Inspection” can be used to quickly and easily evaluate the readiness of laboratory safety equipment. According to the OSHA Laboratory Standard, safety equipment should be checked on a regular basis. It is a good policy to document all safety inspections. If problems are found, repairs should be made promptly.