Force on a Current-carrying Conductor

Cards (31)

  • A current-carrying conductor produces its own magnetic field
    • When interacting with an external magnetic field, it therefore will experience a force
  • A current-carrying conductor will only experience a force if the current through it is perpendicular to the direction of the magnetic field lines
    • A simple situation would be a copper rod placed within a uniform magnetic field
    • When current is passed through the copper rod, it experiences a force which makes it move
    • This phenomenon is sometimes referred to as 'the motor effect'
    • The direction of the force is determined by Fleming's left-hand rule
  • A current-carrying conductor will only experience a force if the current through it is perpendicular to the direction of the magnetic field lines
    A) uniform
    B) electrons
    C) copper
    D) current
    E) copper
    F) force
    G) current
    H) on
  • Two ways to reverse the direction of the force (and therefore, the copper rod) are by reversing:
    • The direction of the current
    • The direction of the magnetic field
  • The direction of the force (aka the thrust) on a current carrying wire depends on the direction of the current and the direction of the magnetic field
    • All three will be perpendicular to each other
    • This means that sometimes the force could appear to be acting either into or out of the page
  • The direction of the force (or thrust) can be worked out by using Fleming's left-hand rule:
    A) thrust
    B) field
    C) current
  • How to find things using the Fleming LH
    • Step 1: Determine the direction of the magnetic field
    • Start by pointing your First Finger in the direction of the (magnetic) Field.
    • Step 2: Determine the direction of the current
    • Now rotate your hand around the first finger so that the seCond finger points in the direction of the Current
    • Step 3: Determine the direction of the force
    • The THumb will now be pointing in the direction of the THrust (the force)Therefore, this will be the direction in which the wire will move
  • Remember that the magnetic field is always in the direction from North to South and current is always in the direction of a positive terminal to a negative terminal.
    • Feel free to use Fleming's left hand rule in your exam, just don't make it too distracting for other students!
  • When a current-carrying wire is placed in a magnetic field, it will experience a force if the wire is perpendicular
    • This is because the magnetic field exerts a force on each individual electron flowing through the wire
  • When a charged particle passes through a magnetic field, the field can exert a force on the particle, causing it to deflect
    • The force is always at 90 degrees to both the direction of travel and the magnetic field lines
    • The direction can be worked out by using Fleming's left-hand rule
  • In the case of a electron in a magnetic field the second finger points in the opposite direction to the direction of motion
    • Conventional current is said to flow opposite to the direction of flow of electrons
    • The finger represents current
    • An alternative is to use the right hand to work out directions for charged particles
  • In the case of a electron in a magnetic field the second finger points in the opposite direction to the direction of motion
    A) electron
  • If the electron particle is travelling parallel to the field lines:
    • It will experience no force
    • If the electron particle is travelling perpendicular to the field lines:
    • It will experience the maximum force
  • If the electron particle is travelling at an angle to the field lines:
    • It will experience a small force
  • Remember that the direction of current is the direction of positive charged. Therefore, if a particle has a negative charge (such as an electron), then the second finger (current) must point in the opposite direction to its direction of travel.
    • The left-hand rule can be applied to any charged particles, but in the IGCSE exam questions are likely to stick to electrons.
  • If 2 parallel wires have opposite travelling currents, magnetic field generated between the two is the same decision
    • wires repel eachother - magnets with like poles repel
  • Wire moves because magnetic field of permanent magnet reacts with magnetic field aka motor effect
  • Current-carrying conductor - conducts anything with current
  • If 2 parallel wires have opposite travelling currents, magnetic field generated between the 2 is the same direction
    • wires repel eachother - magnets with like poles repel
  • Wires move because magnetic field of the permanent magnet reacts aka motor effect
  • Current-carrying conductor - conducts anything with current
  • 3-way switch - one way for one circuit, other war for another circuit
    • middle = open
  • Circuit in series:
    • same → repelling
  • Circuit in parallel
    • opposingattractionn
  • Motor effect - LH rule
    • middle → current
    • thumb → movement
    • index → magnetic field
  • Force factors - magnitude of the force depends on the current, strength of magnetic field, length of the wire, angle between the lines of the force of the field and current direction
  • Force is:
    • greatest when wire is at 90 degrees to the magnetic field
    • 0 when wire is parallel to the magnetic field
  • If a beam of charged particles pass through a magnetic field, there is a force on it, just like current in the wire
  • What will happen to the turning force of a coil if you decrease the current passing through?

    Decreasing the current passing through a coil immersed in a magnetic field will decrease the turning force (torque) on the coil
  • The force experienced by current-carrying wires in magnetic fields is caused by
    the motor effect