Current Events

  • Atmospheric CO2 Level Tops 400 ppm
    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm rep...Read more

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    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
  • Massive Tornado Outbreak on Tornado Alley
    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Io...Read more

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    Massive Tornado Outbreak on Tornado Alley

    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Iowa, Illinois and Missouri. On May 20th, a massive tornado struck Moore, Oklahoma, devastating communities - destroying over 100 homes and hitting two elementary schools and a hospital - with many casualties and deaths. Our thoughts are with our friends and colleagues suffering from these storms. For more on the May 20th storms, see the NOAA Storm Prediction Center Storm Report.
  • Kansas Legislator Proposes Bill to Outlaw Sustainability Education
    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of ...Read more

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    Kansas Legislator Proposes Bill to Outlaw Sustainability Education

    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of sustainability. Here is a link to the one-page bill: http://www.kslegislature.org/li/b2013_14/measures/documents/hb2366_00_0000.pdf. See report on Bloomberg News.

Bar Magnet, Compass, and Magnetic Field Lines Interactive

Have you ever seen someone sprinkle iron filings over a magnet to show the magnetic field around it? This interactive does almost the same thing!

The red and green rectangle (below) is like a bar magnet. The smaller, red and green diamond is like a compass needle. Drag the compass needle to explore the magnetic field around the bar magnet.

Red stands for the north pole of both the bar magnet and the compass needle. Green stands for the south pole of both the magnet and the needle.

This interactive uses Java software. If you can't see the interactive, you may not have Java on your computer.

© Walter Fendt, April 20, 2001

The original version of this applet can be found at Walter Fendt's web site at www.walter-fendt.de/ph11e/mfbar.htm. Other Java applets by Walter Fendt related to physics topics are available at www.walter-fendt.de/ph11e.

Click on the magnetic needle and hold down the mouse button. You'll see a blue magnetic field line appear through the center of the compass needle. When you let go of the mouse button, the field line is "frozen" in place. You can draw more field lines by clicking on the compass needle and dragging it to another place.

Arrows on the magnetic field line show the direction of the field. Magnetic field lines "flow" from the north pole of a magnet to its south pole. That's the direction that the north pole of a compass needle points.

If you want to start over, click the "Clear field lines" button. That will erase all of the field lines you have drawn so far.

If you click the "Turn magnet" button the magnet will flip over. It will turn so its north pole is on the right and its south pole is on the left.

Interactive link Interactive animation: Bar Magnet & Compass (using Flash software)

Interactive link Interactive animation: Earth's Magnetic Field

Interactive link Earth's North Magnetic Pole interactive

Activity link Activity: Build a Magnetometer and use it to detect magnetic fields!

Last modified February 20, 2008 by Randy Russell.

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