Motion of charges in electric and magnetic fields

Learning objectives

Calculate the magnetic force on a current-carrying conductor from F = BIL sinθ, and determine its direction using the left-hand rule

Calculate the magnetic force on a moving charge from F = qvB sinθ, and explain why this force can change the direction of the velocity but never does work on the charge

Analyse the circular path of a charged particle moving perpendicular to a uniform magnetic field, deriving r = mv/(qB) and showing that the period is independent of speed

Describe the motion of a charged particle accelerated through a potential difference, using qV = ½mv², and then deflected on a parabolic path by the uniform field between parallel plates

Explain the force between two long parallel current-carrying conductors, stating that parallel currents attract and antiparallel currents repel, and calculate the force per unit length between them

Analyse arrangements in which electric and magnetic forces act together on a charged particle, such as a velocity selector in which qE = qvB