electric fields unit 4

 people handling microchips wear antistatic clothing and work in rooms filled with antistatic flooring explain why damage to microchip by charge potential difference between chip and body will create an electric field flow of charge that could damage inside the chipantistatic clothing prevents build up of charge on person antistatic flooring prevents transfer of charge there are only two kinds of charge positive and negative charge of the same kind repel each other charge of different kinds attract each other the amount of charge is called the quantity of electricity quantity of positive charge is a positive number quantity of negative charge negative number charge cannot be created or destroyed but moved from one object to another or from one part of a body to another total amount of charge in the body in the transfer process remains the same this is called the law of conservation electrons and protons carry the same amount of different charge quantity of charge e is given on data sheet quantity of all charged objects is equal to either e or its multiple therefor the quantity of charge e is called the elementary charge Columbus law the magnitude of F the electrical force exerted by one point charge on another point charge is directly proportional to the magnitudes q1 and q2 and inversely proportional to the square of the distance r between the charges F = Kq1q2/r2 where k is constant and is 1/4pie0 where e0 is the permitivity of free space f is often called the electrostatic force regardless of whether the forces are attractive or repulsive they are directed along the line between the charges and have equal magnitude each charge exerts a force of magnitude F on the other what are the units for electric field strength Jm-1C-1JA-1s-1m-1NA-1s-1 define the electric potential at a point in an electric field work done per unit charge on a small positive test charge in moving the charge from infinity to the point if got parallel plates with +3v at top and +1v at bottom the electric field direction is downwards an ion travels horizontally and enters a uniform vertical electric field the horizontal component of the velocity of the ion is unaffected by the electric field the electric field that exists at a point is the electrostatic force experienced by a small positive test charge placed at that point divided by the charge itself electric field is a vector and its direction is the same as the direction of the force F on a positive test charge SI unit of electric field NC-1 it is the .... in the environment that create an electric field at a given point charges the field exists in a sense that whenever a positive or negative charge is placed at that point the field exerts a force on the charge any charge in the environment contributes to electric field that exists at a point to determine the net electric field it is necessary to determine the various contributions separately and then find the vector sum of the contributions the electric field produced by a point charge q can be obtained in general terms from Columbus first law , magnitude of force on positive test charge = F = kq0q/r2where q0 is the positive test charge divide by q0 to obtain magnitude of electric field E = kq/r2 so electric field doesn't depend on test charge electric field disregards whether charge is negative or positive electric field lines go from positive to negative of q is positive then E is directed away from q if q is negative then E is directed towards q in an electric field when moving positive test charge from point a to point b the work done is equal to difference between the electric potential energy at B and that at A W = EpEb - EpEa the work done to move the charge from a to b depends on the magnitude of the charge W = q0 x V V is the electric potential energy per unit positive test charge SI unit of electric potential is JC-1 = volt a positive test charge accelerates from a region of higher potential to a region of lower potential conversely a negative test charge accelerates from a region of lower potential to a region of lower potential electric potential at a distance r from a point charge is V = kq/r the previous expression for v assumes the potential is zero at infinite distance away from the charge see diagram from notes in the electric field E the work done required to move a negative test charge from a to b is W= FΔr where F is the magnitude of the applied force directed to the left in opposition of the electric force where r is the distance between a and b E = -ΔV/Δr V = -EΔr W/Q = V W = QEΔr if the test charge is moved at a constant speed the magnitude of the applied force equals the magnitude of the electric force but in the opposite direction so F = -EQ the minus sign in the above equations indicates E is in the direction of decreasing potential an alternate unit for electric field E is Vm-1 comparison of electric fields and gravitational fields  source  gravitational force exists between any two objects with masselectric force exists between any two objects with charge  magnitude of force  newtons law of universal gravitational constant F = GMm/r2G is the universal gravitational constant Newtons law of gravitation for the force between two point masses is an inverse square law - F Ø 1/r2coloumbs law F = 1/4pie0 x q1q2/r2 where e0 is the permitivity of free space coloumbs law for the electric force between two point charges is an inverse square law F Ø r2  direction of force  always attractive  can be attractive or repulsive  field strength  is the gravitational force per unit mass g = GM/r2 , so field around a mass is proportional to the quantity of mass and inversely proportional to the square of the distance between the centre of mass M and the point in space where the field is measured  is the electric force per unit charge , E = 1/4pie0 x Q/r so field around charge is proportional to the quantity of charge and inversely proportional to the square of the distance between the centre of charge Q and the point in space where the field is being measured  potential in radial field  V = -GM/r , gravitational potential energy is the work done per unit mass on a small mass in moving the mass from infinity to that point . gravitational potential is zero at infinity .  V = 1/4pie0 x Q/r , electric potential is the work don per unit charge on a positive test charge in moving the charge from infinity to that point . electric potential is zero at infinity .  line of force or field line  path of free test mass in the field  path of free positive test charge in a field  unit of field strength  NKg-1 or ms-2 NC-1 or Vm-1 unit of potential  JKg-1 JC-1 or V  uniform fields  g is the same everywhere , field lines parallel and evenly spaced  E is the same everywhere , field lines parallel and evenly spaced Authorghoran ID293719 Card Setelectric fields unit 4 Descriptionrevision Updated2015-01-25T11:29:47Z Show Answers