Doctors in Australia have identified twins apparently created from one egg and two sperm, a boy and a girl, the second time such twins have ever been reported. Continue reading
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.
Reveal the science behind sprouting seeds and water conservation.
Nothing compares to eating fresh vegetables picked right out of the garden! But, what’s happening out of sight in the soil of that garden? Here are two plant-growing activities you can do anytime of the year to discover the science behind those growing marvels and to discover a unique way to conserve water, too.
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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.
As most investigations do, this one began with a question. I had a log delivery to my house. The logs were primarily birch. What caused the damage to the birch trees that I was chopping up for wood? The holes were too shallow to suspect woodpeckers. I peeled off the bark, fully expecting to see insect galleries. There were none, but my internet search soon yielded pictures of similar damage caused by sapsuckers.
Some of my bird feeding stations have fat to attract woodpeckers. And so, I stood vigil to see if the fat might attract sapsuckers as well. Pictures from my reference book aided the identification.
Setting up a bird feeding station at school would be easy. The cost is minimal and there is no complicated storage. The seed could be stored in class in a steel trash bin. The lid should seal well to prevent attracting mice or other rodents.
Students could participate by taking turns filling the stations. Throwing in a few old logs and stumps would provide a natural setting. Identifying the birds and studying their ecological niche would be a great science activity. Students could also take part in the bird feeder surveys that are advertised from time to time.
Thanks for the submission Dave!
Retired astronaut Chris Hadfield helps debunk (and confirm!) some common myths about space. Is there any sound in space? Does space smell like burnt steak? Is NASA working on warp speed? ONE STRANGE ROCK airs Mondays at 10/9c on National Geographic. Continue reading