Physics: 1903

1) Becquerel, Antoine Henri

Becquerel, Antoine Henri, pronounced beh KREHL or behk uh REHL, ahn TWAHN ahn REE (1852-1908), was a French physicist. He shared the 1903 Nobel Prize in physics with Pierre and Marie Curie for his discovery of natural radioactivity. In 1896, Becquerel found that rays coming from a uranium ore affected a photographic plate in the same manner as X rays. These rays did not seem to be related to any external source of energy, such as the sun, and were more powerful than the radiation from pure uranium. Following his suggestion, the Curies worked on the substance pitchblende and isolated from it the chemical element radium.

Becquerel was born in Paris on Dec. 15, 1852. His father and grandfather also were physicists. Becquerel studied at the Ecole Polytechnique and graduated as an engineer from the Ecole des Ponts-et-Chaussees. In 1892, he became professor of physics at the Museum of Natural History, and in 1895 took the same position at the Ecole Polytechnique. He was elected president of the French Academy of Sciences in 1908. Becquerel died on Aug. 25, 1908. The becquerel, a unit of radioactivity, is named for him.

2) Curie, Pierre

Curie, Pierre, pronounced KYOO ree, pyair (1859-1906), was a French physicist known for his work in radioactivity. He shared the 1903 Nobel Prize in physics with his wife, Marie, for their study of radiation and with the French physicist Antoine Henri Becquerel for his earlier discovery of natural radioactivity. The Curies, while studying uranium, discovered two highly radioactive chemical elements, radium and polonium. A co-worker, Gustave Bemont, helped in the work with radium.

Curie was born in Paris and studied and taught physics at the University of Paris. His early work involved research on the magnetic properties of metals. The temperature at which such properties suddenly change became known as the Curie point. In 1880, Curie and his brother Jacques published a paper about their discovery of the piezoelectric properties of crystals.

3) Curie, Marie Sklodowska

Curie, Marie Sklodowska, pronounced KYOO ree,pronounced sklaw DAWF skah (1867-1934), was a Polish-born French physicist who became famous for her research on radioactivity. She was the first woman awarded a Nobel Prize and the first person to win two Nobel Prizes, receiving one in physics and one in chemistry. She was also the first woman to teach at the Sorbonne, a famous university in Paris.

Curie and her husband, Pierre, also a physicist, worked together in the late 1890's to study the radiation given off by such chemical elements as uranium and thorium. They found that uranium ore called pitchblende gave off much more radiation than could be accounted for by the amount of uranium known to be in the ore. The Curies then searched for the source of the additional radiation. In 1898, they announced their discovery of two previously unknown, highly radioactive elements, which they named radium and polonium. They worked to separate tiny amounts of these elements from tons of pitchblende.

Marie theorized that radioactivity was a property linked to individual atoms rather than one that depended on the arrangements of atoms in molecules. Later, other scientists showed that polonium and radium were created by a process called radioactive decay or transmutation of the original uranium atoms. That is, the uranium atoms had changed from one element into another by giving off radiation. Previously, scientists had not known that atoms could change in any way.

The Curies' work was inspired by Antoine Henri Becquerel, a French physicist who had also conducted research on radiation. In 1903, Becquerel and the Curies won the Nobel Prize in physics. Becquerel received the award for discovering natural radioactivity and the Curies for their study of radiation. In 1911, Marie Curie won the Nobel Prize in chemistry for her discovery of the new elements and her work in isolating radium and studying its chemical properties.

Marie Curie was born Marya Sklodowska in Warsaw, Poland, which was then ruled by Russia. Both of her parents were teachers. She met Pierre Curie in Paris, where she studied mathematics, physics, and chemistry. She died in 1934 of leukemia, probably caused by years of exposure to radiation.

Piezoelectricity

Piezoelectricity, pronounced pee ay zoh ih lehk TRIHS uh tee, is an electric phenomenon that occurs in certain nonmetallic minerals, such as quartz, Rochelle salt, and tourmaline. These crystals develop an electric charge on their surfaces when they are stretched or compressed along an axis. In addition, voltage applied to such crystals causes them to expand and contract, producing vibrations. Crystals that have these properties are called piezoelectric crystals. Pierre and Jacques Curie, two French physicists, published their discovery of piezoelectricity in 1880.

Piezoelectricity has many uses. Piezoelectric crystals control the frequency of electric current in radio transmitters. The crystals are cut so that only signals of a certain frequency can pass through them. Piezoelectric crystals in a phonograph pickup cartridge convert the vibrations of the phonograph needle into a varying electric signal. Piezoelectric crystals are also used in microphones and other electronic devices that change sound waves into electric signals.