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Φυσική και Φωτογραφία - Ηλεκτρομαγνητικές Ταλαντώσεις Powered by 3DENΠλήρη Οθόνη Λίγα λόγια για την αυτεπαγωγή Όταν ένα πηνίο διαρρέεται από μεταβαλλόμενο ηλεκτρικό ρεύμα εμφανίζει ΗΕΔ από αυτεπαγωγή. Αν θεωρήσουμε ως θετική φορά την φορά του ηλεκτρικού ρεύματος τότε η επαγωγική ΗΕΔ θα δίνετε από την εξίσωση το νόημα του πρόσημου είναι ότι όταν η ΗΕΔ από αυτεπαγωγή είναι αρνητική τότε η πολικότητά της είναι τέτοια ώστε να δίνει ρεύμα προς την αρνητική φορά ενώ όταν είναι θετική δίνει ρεύμα προς την θετική. η διαφορά δυναμικού στα άκρα του πηνίου κατά την φορά του ηλεκτρικού ρεύματος θα είναι πάντα Διερεύνηση : α) αν το ρεύμα αυξάνεται δηλαδή όταν τότε δηλαδή η πολικότητα της πηγής θα είναι αντίθετη με την φορά του ηλεκτρικού ρεύματος (προσπαθεί η πηγή να ελαττώσει το ρεύμα πράγμα σύμφωνο με τον κανόνα του Lentz) και δηλαδή το σημείο απ' όπου εισέρχεται το ηλεκτρικό ρεύμα έχει υψηλότερο δυναμικό από το σημείο που εξέρχεται β) αν το ρεύμα ελαττώνεται ( το δυναμικού του σημείου από όπου εισέρχεται το ηλεκτρικό ρεύμα είναι μικρότερο από όπου εξέρχεται. ή με

Special Issue: From mammoths to Neandertals, ancient DNA unlocks the mysteries of the past Skip to main content ScienceShot Special Issue: From mammoths to Neandertals, ancient DNA unlocks the mysteries of the past Email Elizabeth By Elizabeth Culotta 0 Comments Ancient DNA researchers have succeeded beyond all expectation in retrieving entire genomes from-long dead organisms, and their work is transforming the study of the past, as discussed in Science’s special news package and in the video above. Ancient DNA package: (Video credit: Science) Posted in Archaeology, Evolution Science| DOI: 10.1126/science.aac8901 Stink bugs protect their eggs by changing their color Surprise: Snakes don’t kill by suffocation Scientists arm cells with tiny lasers Great Recession was good for the environment The benefits of band class Video: Battle wound may reveal bones of Alexander the Great's father Arctic sea ice enjoyed a brief—but temporary—respite from melting in 2013 Video: Solving the mystery of the invisible 'sea sapphire' Previous Video Next Video Popular Follow Us

Discover the COSMOS Khan Academy Sea level study: James Hansen issues dire climate warning. Photo by Joe Raedle/Getty Images In what may prove to be a turning point for political action on climate change, a breathtaking new study casts extreme doubt about the near-term stability of global sea levels. The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer-reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates.

i2geo - WebHome How do you measure the earth's circumference? Simply using the sun, a stick, similar triangles, and… communication. Eratosthenes did it centuries ago. It possible to do that with pupils next Friday, March 21st. To this end: register on find a partner school, go out and measure. Continue Reading Welcome to Halle! The i2geo server was moved to Halle, Germany.Continue Reading CADGME-2012 in Novi Sad After a successful conferences held at Pécs, Hungary (2007), Hagenberg, Austria (2009) and Hluboká nad Vltavou, Czech Republic (2010) we are delighted to announce that the CADGME conference continues. Find more on Reading i2geo in new shoes I am happy to announce that we successfully moved i2geo.net to the PH Karlsruhe.Continue Reading JSXGraph @ MathFuture - meet the new DGS The emerging Dynamic Geometry System JSXgraph will be presented online in the DGS Series of MathFuture.

Υλικό Φυσικής-Χημείας. Innovative Brain Imaging Combines Sound And Light Lihong Wang uses light and sound to create highly detailed images of the living brain. Chris Nickels for NPR hide caption toggle caption Chris Nickels for NPR Lihong Wang uses light and sound to create highly detailed images of the living brain. Chris Nickels for NPR Lihong Wang creates the sort of medical technology you'd expect to find on the starship Enterprise. Wang, a professor of biomedical engineering at Washington University in St. "It's really about turning some of these ideas that we thought were science fiction into fact," says Richard Conroy, who directs the Division of Applied Science & Technology at the National Institute of Biomedical Imaging and Bioengineering. Wang's ultimate goal is to use a combination of light and sound to solve the mysteries of the human brain. Wang describes himself as a toolmaker. "We want to conquer the brain," Wang says. Current brain-imaging techniques such as functional MRI or PET scans all have drawbacks. Wang's initial idea was to use light.

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