Name:

Science Teacher:

Year:

Explanation:

Yasuhiro

Dina Srouji

September 11, 2001

This is first or one of the first assignments that i got for science class. Also this is the first or one of the first assignments i got a seven on in science class. Its odd, I got one of my first sevens on a work done on September 11.

Microscopes first appeared about 2000 years ago. The first kinds of microscopes were magnifying glasses. A few examples are, water-filled glass globes, which was used by engravers and rock crystal, which the Romans used. In the late 1200's glass lenses were created. The glass lenses gave a new era to microscopes because later in the years, compound, single-lens, electron, and ion microscopes were invented.

Much credit goes to Zacharias Janssen, a Dutch optician, who discovered the compound microscope in 1590. Somewhere in the 1670's, Anton Van Leeuwenhoek, a Dutch scientist, made a single-lens microscopes. The microscope was amazing because it could have magnified up to 270x. As a few more years passed, it improved the glass-making methods, so it did not create distorted images. In 1931, Ernst Ruska and other German scientists invented the first electron microscope. The electron microscope used a beam of electrons to magnify an object's image and it gave clearer pictures than the optical microscope that enlarged the object 2,000 times. The electron microscope enlarged the object by 1,000,000 times. Later in 1951 Erwin W. Muller, a German physicist, invented the ion microscope. The ion microscope was so sharp the individual atoms can be seen. In 1981 Swiss and West German scientists invented the scanning tunneling microscope that scans a specimen with sharp point called probe. This kind of microscope was a scanning probe microscope. The scanning tunneling microscope uses electric currents that flow between the probe and the specimen, so a computer can get its measurements and form a picture. The other kind of scanning probe microscope was a atomic force microscope, which is just like the scanning tunneling microscope except it did not ouch the specimen with the probe.