Practicals

• Springs?

  • Fix the top of a spring to a clamp on a retort stand
  • Also fix a ruler next to it, with the zero mark lined up with the bottom of the spring
  • For accurate measurements, make sure ruler is as close to spring as possible
  • Get on eye level to do so
  • This reduces parallax error
  • Add slotted masses on a hanger to the spring to charge force/tension

  IV: force

  DV: extension

  CV: same spring
• Newton's 2nd Law?

  • Attach slotted masses to a trolley on a track
  • This is so they hang over a pulley
  • Let trolley move due to the weight of masses - its flag will pass through two light/photogates connected to a datalogger, which calculates acceleration
  • Change the force by removing masses from the hanger and placing them on trolley
  • The total mass being accelerated must remain constant

  IV: force

  DV: acceleration

  CV: mass being accelerated, same trolley
• Waves (Ripple tank)?

  • Project image of ripple tank onto paper
  • Using a strobe light connected to the signal generator makes it easier to measure the length of 10 complete waves
  • Divide by 10 to get the wavelength
  • Repeat for different frequencies

  IV: Frequency

  DV: Wavelength

  CV: Depth of water
• Waves (Stationary wave on string)?

  • Change frequency until the simplest stationary wave is formed on the string
  • At this point, the wavelength is 2 x length of string
  • Vary frequency and move oscillation/bridge to repeat

  IV: Frequency

  DV: wavelength

  CV: type of string, mass on end
• Infa-Red emission?

  • Fill a leslie cube with hot water from a freshly-boiled kettle
  • Use an IR detector/thermometer to measure relative emission of IR from the different surfaces
  • Use a ruler to ensure the distance is the same every time (control variable)
• Infa-Red Absorption?

  • Put thermometer and bung in test tubes with different materials wrapped around
  • Place the test tubes the same distance from a lamp/IR lamp

  Matte black is the best absorber and emitter. Shiny surfaces are the worst at both
• Refraction?

  • Place glass/perspex block on a piece of paper
  • Shine light from a ray box in at an angle
  • Draw around the block, and mark the point of origin of the ray, as well as its entry and exit points, and the normal (90 degrees to the surface)
  • Measure the angle of incidence and angle of refraction from the normal
  • Repeat for varying angles of incidence, calculate refractive index for each repeat

  IV: angle of incidence

  DV: angle of refraction

  CV: ray box, material of box