Voldemort, alive again, summons his Death Eaters, berates them for believing him dead, and mentions that he has a single 'faithful servant' concealed at Hogwarts, who has led Harry to the graveyard for the resurrection. He tortures Harry, then challenges him to a duel to prove his prowess. However, when he and Harry fire spells at each other, their wands connect unexpectedly, causing echoes of Voldemort's previous magic to appear, including manifestations of Cedric and Harry's parents. These echoes provide a distraction for Harry, who escapes with Cedric's body to the Cup, which takes him back to Hogwarts.
Under the panic caused by his arrival, Moody takes a traumatised Harry to his office. He reveals himself to be Voldemort's 'faithful servant.' He explains that he put Harry's name into the Goblet of Fire under a different school and has been guiding him through the tournament to ensure he would touch the Cup first: he gave him the hint about flying, staged a conversation about Gillyweed in front of Dobby, cursed obstacles from outside the hedge maze, and used the Imperius Curse on Krum to force him to curse Cedric. As Moody prepares to kill Harry, Professors Dumbledore, McGonagall, and Snape intervene and stun Moody. Slowly, Moody changes appearance to become Barty Crouch Jr., the supposedly long-dead son of Barty Crouch Sr., who was using Polyjuice Potion to impersonate Moody.
Using Veritaserum, a truth potion, they learn that Barty Crouch Sr. rescued his son from Azkaban as a favour to his dying wife: the Crouch Jr. who died in Azkaban was his mother, disguised under Polyjuice Potion. Crouch Jr. was kept imprisoned at home. Winky convinced Crouch Sr. to allow Crouch Jr. to see the Quidditch World Cup, where he stole Harry's wand, escaped, and conjured the Dark Mark. Wormtail, meanwhile, had captured Bertha Jorkins, who had once seen Crouch Jr. at home and been bewitched to forget. This allowed Voldemort to discover Crouch Jr.'s whereabouts, then formulate a plan to install Crouch at Hogwarts and lead Harry to him. Crouch Sr. was imprisoned by Wormtail, and when he escaped to Hogwarts, Crouch Jr. killed him.
Dumbledore explains that Harry's and Voldemort's wands connected because they share a core of a feather from the same phoenix, coincidentally Dumbledore's own phoenix Fawkes.
Dumbledore announces Lord Voldemort's return to the school. However, many people, including Minister for Magic Cornelius Fudge, refuse to believe it. Fudge hastily has the Dementor's Kiss performed on Crouch Jr., who is thus unable to give testimony proving Voldemort's return. Dumbledore puts his own anti-Voldemort plans into action.
Hermione discovers Rita Skeeter is an unregistered Animagus who can take the form of a beetle, allowing her to eavesdrop on secrets. She blackmails Skeeter to force her to stop writing her libelous stories. Not wanting his tournament winnings, Harry gives all one thousand Galleons to Fred and George to start their joke shop, and returns home with the Dursleys.
Crohn's disease
Crohn's disease is a disease that causes the intestines to become swollen. It is a type of inflammatory bowel disease (IBD). The intestines may also develop ulcers. People with Crohn's disease often have pain in the stomach, diarrhea, vomiting, and weight loss. Crohn's can also cause skin rashes, arthritis, and swollen eyes. It is named after Burrill Bernard Crohn, who described cases in 1932. It was first
described by Giovanni Battista Morgagni (1682–1771) in the 18th century.
Nobody knows exactly what causes Crohn's disease. In the disease, the person's body attacks itself. The immune system attacks healthy parts of the digestive tract. This causes swelling in the digestive tract.
Though Crohn's is an immune-related disease, it is not an autoimmune disease (the immune system is not triggered by the body itself). The exact underlying immune problem is not clear. Crohn's disease seems to be connected to the person's genes. People whose brothers or sisters have the disease are the most likely to get it. Men and women can both be affected by Crohn's disease.
Managing Crohn's disease includes both lifestyle changes and various kind of medication. It is a chronic condition for which there is no cure. Certain parasitic intestinal worms appear to make the bowel less inflamed. It is supposed that the worms modify the immune reactions in the parts of the intestine where they live.
Alternative medicine of various kinds has been tried, with uncertain results.
Pet door
Pet doors, also known as cat doors, dog doors, doggie doors, or in the United Kingdom, cat flaps, are small doors for pets. They are usually built in regular doors, but can also be in windows or walls. They usually have the hinge on the top, with no latch, so the animal can push their way in and out. Newer models sometimes only let the pet go outside, but not inside. Others have a latch and something that can be put on the pet that makes the latch open when the pet gets close to the door. They are most commonly used for pet cats, but can also be used for dogs, miniature pigs, or other small pets.
The pet door was developed by Isaac Newton.
Mount Rainier
Mount Rainier is a mountain 54 miles (87 kilometres) southeast of Seattle, Washington, in the United States. The volcano is the highest mountain in the Cascade Range, at 14,410 feet (4,392 metres). The top of the mountain is mostly covered by snow and glaciers. Rainier is an active volcano, but has not had an eruption for more than 100 years. Some describe Rainier as dormant or inactive.
On March 2, 1899, U.S. President William McKinley made the mountain and area around it Mount Rainier National Park. It was the country's fifth national park.
Fort Knox
Fort Knox is an U.S. Army post in Kentucky. Named after Henry Knox, the fort is now the site of the U.S. Bullion Reservatory (where the United States keeps its gold). The fort's fortifications were built in 1862 during the American Civil War; however, after the war the camp became abandoned until 1917.
It is named for Henry Knox, a general in the American Revolutionary War.
Maxwell's equations
Maxwell's equations describe how electric charges and electric currents create electric and magnetic fields. They describe how an electric field can generate a magnetic field.
In the 1860s James Clerk Maxwell published equations that describe how charged particles give rise to electric and magnetic force per unit charge. The force per unit charge is called a field. The particles could be stationary or moving. These, and the Lorentz force equation, give everything one needs to calculate the motion of classical particles in electric and magnetic fields.
The first equation allows one to calculate the electric field created by a charge. The second allows one to calculate the magnetic field. The other two describe how fields 'circulate' around their sources. Magnetic fields 'circulate' around electric currents and time varying electric fields: Ampère's law with Maxwell's extension, while electric fields 'circulate' around time varying magnetic fields: Faraday's law.
where the following table provides the meaning of each symbol and the SI unit of measure:
and
where formula_4 is the "free" electric charge density (in units of C/m), not counting the dipole charges bound in a material, and formula_5 is the electric displacement field (in units of C/m). This equation is like Coulomb's law for non-moving charges in vacuum.
The next integral form (by the divergence theorem), also known as Gauss' law, says the same thing:
formula_7 is the area of a differential square on the closed surface A. The surface normal pointing out is the direction, and formula_8 is the free charge that is inside the surface.
In a "linear material", formula_5 is directly related to the electric field formula_10 with a constant called the permittivity, formula_11 (This constant is different for different materials):