Assignment on physics-iiSubmitted by

Md Jahid Hasan

Id-152-15-5588

Sec-A

Submitted to

Jebun naher sikta

Dep.of CSE

Lecturer on natural science

Daffodil international university

Assignment on Rotational motion of electron-

Defination of centrifugal force:A force that tends to move objects away from the center in a systemundergoing circular motion. Centrifugal force keeps the water in a whirlingbucket from spilling or throws a rider in a car against the door when the cargoes around a sharp curve. Centrifugal force is actually a form of inertia. a force, arising from the body's inertia, which appears to act on a body moving in a circular path and is directed away from the centre around which the body is moving.

Where does electron gets centrifugal force:The centrifugal force of the revolving electron just exactly balances the attractive force of the

nucleus

a planet or a satellite, is electrically charged  and it has been known since the mid-19th century that an electric charge that undergoes acceleration (changes velocity and direction) will emit

electromagnetic radiation, losing energy in the process. A revolving electron would transform the atom into a miniature radio station, the energy output of which would be at the cost of the potential energy of the electron.

actually electrons revolve around the nucleus and centripetal force holds them in the specified orbits it just not hold them in orbits but also is the cause of electrons rotation around nucleus because electrons and nucleus are connected to each other with this force like in a cycle wheel the tire is connected to the wheel excel with spokes excel rotates then tire also rotate similarly electrons also rotate around nucleus because nucleus is also rotating about its own axis causes the electrons to rotate around it .this gives the answer why electrons not require nor lose energy revolving around nucleus .when viewed from an inertial reference frame,a body in circular motion only requires a centripetal force.However to apply the inertial laws of motion from the electrons point of view we must include an imaginary pseudo-force,which is the centrifugal force. The centrifugal force acts on the source of the centripetal force to displace it radially from the center of the Electron path.Its’s clear that ,electron get centrifugal force from the center of its rotation path.

Why electron rotate in a orbit:Earth rotates around the sun because of sun's gravity. If the sun would not have been there Earth would move in a straight line

but because of the Sun's gravitational influence its course is altered and it moves in a nearly

circular path.. Similarly, moon rotates around Earth due to Earth's gravitational influence. The velocity of these bodies helps to balance the force and prevents the body from falling into the host body and maintain a orbit.Electron rotate in orbit because of maintain circumstance. Electrons are present outside the nucleus and are negatively charged. Nucleus consists of protons and neutrons, protons are the positive guys. Positive and negative charges develop a attractive force known as Coulomb Force of attraction. This force helps the electron to rotate in its orbit. If electrons rotate, they must release energy and fall into the nucleus.Here comes Neil Bhor's theory to rescue. Electrons move in specialized energy shells named K,L,M,N etc and electrons jump higher and lower shells according to the energy they gain or loose. If they are only given some energy, but not enough to knock them loose, they will move from one orbital to another . But if there is no other electron in the lower-energy orbital, they will fall back down again. When they do, they release energy in the form of a photon (light).Electrons are rotate in orbit,because of electric attraction or binding coulomb potential.

Why electron travel in a cycle:Electrons literally travel in a Cycle. Because the electron is negatively charged it wants to maintain the same average density as the background lattice, which of course having lost electrons is positively charged. If there is a slight excess of electrons at some part of the circuit, the net negative charge there repels further electrons being added. Because the charge density and the lattice are both very large, even very slight imbalances cost a large amount of energy to create, so the acts as an incompressible fluid. From there it's all basically plumbing. Imagine a water pump connected to a loop of pipes Voltage is analogous to water pressure, and current is analogous to water flow. Electrical resistance is analogous to flow resistance in pipes, and energy is literally energy. Capacitance is analogous to the way high pressure water compresses slightly itself causes pipes and closed tanks to expand slightly and causes the water level in open tanks to rise.

Against that background the movement of electrons in a wire is analogous to the flow of water molecules in a pipe. In fact the Drift velocity is relatively slow for typical currents.Because electrons are negatively charged, and because positive current was defined without knowledge that it's normally electrons in

motion, the flow of electrons is opposite to current as standardly defined. There are a few exceptions to the idea that it's always moving electrons carrying (negative) current, but as far as I know, all such exceptions are well understood. For example in Electrolyte , it's not individual electrons moving, but electrons attached to atoms or groups of atoms to form negatively charged ions. And, at the same time positively charged ions drift in the opposite direction and contribute to the overall current flow. Similarly in Extrinsic semiconductor , impurity atoms absorb electrons from the substrate leading to "holes" which move rather as if they were positively charged particles.We also know that electron are attracted nucleus,so electron travel in a cycle.Finally, we can tell that electron travel a cycle for maintain circumstance.

Reference: live science,yahoo,info,physics forums,quora,Wikipedia,physics book.