Physics

• Investigating Motion

  • Set up a trolley with a gap in the middle that will interrupt the signal of a light gate twice. Measure the length of each card that passes through the light gate as it will input it inside the software and be able to measure the velocity
  • With this the acceleration can be worked out
  • Connect the trolley with string that goes over a pulley and is connected on the other side to a hook
• Investigating motion

  • The weight of the hook and any other masses provide accelerating force
  • Mark a starting line so the trolley travels the same distance to the light gate
  • Place the trolley at the starting line then release the trolley
  • Record the acceleration measured by the light gate which is the acceleration of the whole system
  • Repeat twice to get an average acceleration
• Investigating Law of reflection

  • Place a mirror on a piece of paper and draw where the mirror is
  • Use ray box to shine a thin beam of light at the mirror
  • With a pencil mark the centre of the incident ray, the reflected ray and the removal
  • Remove the ray box
  • Draw the incident ray, reflected ray
  • Measure the angle of incidence and angle of reflection with a protractor
• Motor effect

  • current goes through a wire
  • There is a magnetic field around the wire
  • There is a magnetic field around the magnet
  • The two magnetic fields interact to exert a force which moves the wire
  • This is called the motor effect
• What does a force depend on ?

  • magnetic flux density
  • size of the current
  • length of the wire
• uses of electromagnets

  scrapyards, electric bells, speaker
• how to build an electromagnet

  • wrap insulating wire around an iron nail connecting wires on each end
  • plug connecting wire into the power pack and turn it on
  • Electromagnetic field should flow through the magnet and turn it on
• How to test the strength of the electromagnet

  • attempt to pick up the paper clips and count how many are picked up
  • Increase the current to pick up more paper clips
  • and to vary the test increase the current
• How does a direct current motor work?

  current flows through a wire

  there is a magnetic field around a wire

  there is a magnetic field around the permanent magnet

  the magnetic field also exert an equal and opposite force which moves a wire

  There is a split ring commutator that ensures one side of the wire moves up and down which rotates in the same direction

  The split ring commutator swaps direction every half turn
• what are the two roles of a split ring commutator

  swaps direction every half turn and keeps the wire from not tangling up
• how to make a stronger motor

  increase current, increase the number of coils of a wire, increase the magnetic field