New videos from Khan Academy 2021-04-12T17:29:53.000000
Atualizado: 1 hora 56 minutos atrás
Winslow Homer, The Army ofthe Potomac—A Sharpshooter on Picket Duty, 1862, wood engraving on paper, 23.2 x 35.1 cm, illustration in Harper’s Weekly, November 15, 1862 (Smithsonian American Art Museum). Speakers: Sarah Alvarez and Dr. Kimberly Kutz Elliott
Max Ernst, Two Children Are Threatened by a Nightingale, 1924, oil with painted wood elements and cut-and-pasted printed paper on wood with wood frame, 69.8 x 57.1 x 11.4 cm (The Museum of Modern Art, New York) With Dr. Steven Zucker and Dr. Beth Harris
James Abbott McNeill Whistler, Nocturne in Black and Gold, the Falling Rocket, 1875, oil on panel, 60.3 × 46.7 cm (Detroit Institute of Arts) A conversation with Dr. Steven Zucker and Dr. Beth Harris
Volume density is the amount of a quantity (often mass) per unit of volume. Density=Quantity/Volume
Area or surface density is the amount of a quantity (often mass) per unit of area. Density=Quantity/Area
Sal uses place value blocks to regroup and subtract 438-272.
By art21. Artist Mickalene Thomas discusses her use of craft materials, her artistic influences, and the importance of seeing oneself represented in museums.
Join Gaylord Torrence and Brian Vallo for a closer look at, and in-depth commentary on, a selection of highlights in the exhibition Art of Native America: The Charles and Valerie Diker Collection. https://wwwreview.metmuseum.org/exhibitions/listings/2018/art-of-native-america-diker-collection Featuring Gaylord Torrence, Fred and Virginia Merrill Senior Curator of American Indian Art, The Nelson Atkins Museum of Art Basket Bowl https://www.metmuseum.org/art/collection/search/717568 The exhibition is made possible by The Peter Jay Sharp Foundation, the Diane W. and James E. Burke Fund, the Enterprise Holdings Endowment, and the Walton Family Foundation. The Metropolitan Museum of Art is situated in Lenapehoking, the homeland of Lenape peoples, and respectfully acknowledges their ongoing cultural and spiritual connections to the area. Credits Editor: Sarah Cowan Producer: Melissa Bell Audio: David Raymond Photography: Eileen Travell Music: Austin Fisher. Archival images Carrie Bethel, Courtesy Yosemite National Park Archives, Museum, and Library © 2018 The Metropolitan Museum of Art
Michelozzo, Palazzo Medici, Florence, begun 1444 A conversation with Dr. Steven Zucker and Dr. Beth Harris
Manuel Vilar, Tlahuicole, the Tlaxcaltecan General, Fighting in the Gladiatorial Sacrifice, 1851, plaster, 216 cm high (Museo Nacional de Arte, Mexico City) A conversation between Dr. Lauren Kilroy-Ewbank and Dr. Steven Zucker
Since positive chargers accelerate along the field direction, they gain kinetic energy or lose potential energy. So, potential always reduces along the field lines. Negative charges, however, will accelerate against the field lines and lose potential energy along the opposite direction of the field lines.
The potential at a point can be calculated as the work done by the field in moving a unit positive charge from that point to the reference point - infinity. You can also calculate the potential as the work done by the external force in moving a unit positive charge from infinity to that point without acceleration.
To find the sign of work done, check if the direction of the force and the displacement are the same or not. If they are in the same direction, work is positive, else it's negative. When moved slowly, work done by an external force on a charge is always in the opposite direction of work done by the electric force.
Let's explore how the equipotential surfaces look like for two, like and unlike charges, kept close to each other.
Let's calculate potential far away from tiny dipoles.
Let's calculate the electric field vector by calculating the negative potential gradient. We first calculate individually calculate the x,y,z component of the field by partially differentiating the potential function.
Equipotential surfaces have equal potentials everywhere on them. For stronger fields, equipotential surfaces are closer to each other! These equipotential surfaces are always perpendicular to the electric field direction, at every point.
The potential at any point is always an indicator of how much more potential energy a coulomb would have compared to when it's at some reference point. So, if the potential is negative, it means the coulomb at that point would have less potential energy compared to when it's at the reference point. Hence potential at a point is always the potential difference between that point and some reference.
Electric fields can also be thought of a negative potential gradient. In this video, let's explore the meaning of this statement.
Consider a charge q, inside a cavity of a spherical conductor. Let's explore how the induced charges get redistributed in electrostatic conditions.