Filters are used to remove unwanted items and/or impurities in the substance you are filtering.
The most usual thing meant by filter in electrical science is a wave filter. One common kind lets through some frequencies and stops all others. This is a band pass filter. For instance, in a radio it can select the radio station the listener wants to hear. The frequency of that station is passed, but all others are rejected.
There are many other uses, including use in telephones and audio, see: audio crossover.
There are digital filters which can be used to filter things besides frequencies. A common use is to improve the quality of pictures. For instance, there are filters which can make the edges of objects look more clear.
Optical filters act on light. They change it certain ways. This can be used for photographic filters.
Filters can be made from mechanical components. They will do very similar things to electric filters. Most especially, mechanical filters can be wave filters. That is, they can block some frequencies and pass others. Because of this, electric filters are sometimes made by first making a mechanical filter. The electric wave is turned into a mechanical movement, then passed through the filter, then turned back in to an electric wave. This kind of filter is often made from quartz crystals.
A device which changes electrical signals into mechanical signals is called a transducer. A device which changes mechanical signals into electrical signals is also a transducer, but one of a different kind.
An internet filter removes certain kinds of information. For example, certain words can be blocked.
Guwahati
Guwahati is the largest city in the north eastern region of India.
It houses the capital complex of the Legislative Assembly of Assam. The first bridge across the Brahmaputra river is situated at the northwest perimeter of the city. Guwahati serves as the gateway to the rest of the Seven States of Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland and Tripura.
Henry Clay
Henry Clay, Sr. (April 12, 1777 – June 29, 1852) was an American politician from Kentucky. He served in the House of Representatives (as Speaker), in the Senate, and was Secretary of State. He ran for President several times but never won. He wanted the United States to fight the British in the War of 1812. After years in the Democratic-Republican Party he started the Whig Party to oppose Andrew Jackson.
He helped pass the famous compromises over slavery leading up the Civil War, including the Missouri Compromise and the Compromise of 1850. He is considered to be one of the greatest Senators in United States history.
Henry Clay was born on April 12, 1777, at the Clay farmhouse in Hanover County, Virginia, in a story-and-a-half frame house. It was an above-average home for a common Virginia planter of that time. At the time of his death, Clay's father owned more than 22 slaves, making him part of the planter class in Virginia (those men who owned 20 or more slaves). He also ate copious amounts of cabbage to survive the cold winter months.
Henry was the seventh of nine children of the Reverend John Clay and Elizabeth Hudson Clay. His father, a Baptist minister nicknamed "Sir John," died four years after his birth in 1781. The father left Henry and his brothers two slaves each, and his wife 18 slaves and of land. Henry Clay was a second cousin of Cassius Marcellus Clay, who became an abolitionist in Kentucky.
The widow Elizabeth Clay married Capt. Henry Watkins, who was a loving stepfather. Henry Watkins then moved the family to Richmond, Virginia. Elizabeth had seven more children with Watkins, having sixteen.
His stepfather secured Clay employment in the office of the Virginia Court of Chancery, where he showed a skill for law. There he became friends with George Wythe. Wythe chose Clay as his secretary. After Clay was employed as Wythe's faculty for four years, the chancellor took an active interest in Clay's future; he arranged a position for him with the Virginia attorney general, Robert Brooke. Clay received no formal legal education but, as was customary at the time, "read the law" by working and studying with Wythe, Chancellor of the Commonwealth of Virginia (also a mentor to Thomas Jefferson and John Marshall, among others) and Brooke. Clay was admitted to practice law in 1797.
After starting his law career, on April 11, 1799, Clay married Lucretia Hart at the Hart home in Lexington, Kentucky. She was a sister to Captain Nathaniel G. S. Hart, who died in the Massacre of the River Raisin in the War of 1812.
Clay and his wife had eleven children (six daughters and five sons): Henrietta (1800–1801), Theodore (1802–1870), Thomas (1803–1871), Susan (1805–1825), Anne (1807–1835), Lucretia (1809–1823), Henry, Jr. (1811–1847), Eliza (1813–1825), Laura (1815–1817), James Brown, (1817–1864), and John (1821–1887).
Seven of Clay's children died before him and his wife. By 1835 all six daughters had died of many conditions, two when very young, two as children, the other two as young women: from whooping cough, yellow fever, and complications of childbirth. Henry Clay, Jr. was killed at the Battle of Buena Vista during the Mexican-American War.
Lucretia Hart Clay died in 1864 at the age of 83. She is buried with her husband in Lexington Cemetery. Henry and Lucretia Clay were great-grandparents of the suffragette Madeline McDowell Breckinridge, a family member of John C. Breckinridge, who was Vice President of the United States during James Buchanan's presidency.
Daniel Webster
Daniel Webster (January 18, 1782 – October 24, 1852) was an important American statesman. He first became famous because of his defense of New England shipping interests. In his life, he became more and more nationalistic, and convinced many people to become nationalists too. This made Webster one of the most famous orators and powerful Whig leaders of the Second Party System. Webster did not like slavery, but he thought it was more important for the Union (the United States) to stay together than anything else.
Webster became the northern member of a group known as the "Great Triumvirate". They included his colleagues Henry Clay from the west and John C. Calhoun from the south. His "Reply to Hayne" in 1830 was generally seen as "the most eloquent (powerful, fluent, well-spoken) speech ever delivered in Congress."
Webster tried to keep the nation from civil war, and make them have a firm peace. His efforts did not succeed, but he was still respected for them. He was officially named by the U.S. Senate in 1957 as one of its five best members.
Daniel was born on January 18, 1782. His parents were Ebenezer and Abigail Webster (née Eastman) in Salisbury, New Hampshire, now part of the city of Franklin. He and his nine siblings grew up on his parents' farm. Daniel Webster's great-great-grandfather was Thomas Webster (1631–1715). Thomas Webster was born in Ormesby St. Margaret, Norfolk, England and settled in New Hampshire. As Daniel was a "sickly (unhealthy) child", his family often let him have whatever he wanted and he didn't have to work on the farm.
Daniel Webster became a lawyer and politician. He was elected to Congress as a Federalist. He supported free trade, opposed both Abolitionism and the expansion of slavery, and opposed the War of 1812 and other policies of the Democrats. When the Federalist Party declined, he joined with other former Federalists and National Democrats to form the Whig Party (United States). Always Webster supported the unity and harmony of the nation against various divisive schemes.
The Catcher in the Rye
The Catcher in the Rye is a novel by author J. D. Salinger. It was first published in 16 July 1951.