Required Practical's

Required Practical's

1. RP6 - Force and Extension

   • Method
     • Secure a clamp stand to the bench using a G-clamp or a large mass on the base.
       • Use bosses to attach two clamps to the clamp stand.
         • Attach the spring to the top clamp, and a ruler to the bottom clamp.
           • Adjust the ruler so that it is vertical, and with its zero level with the top of the spring.
             • Measure and record the unloaded length of the spring.
               • Hang a 100 g slotted mass carrier - weight 0.98 newtons (N) - from the spring. Measure and record the new length of the spring.
                 • Add a 100 g slotted mass to the carrier. Measure and record the new length of the spring.
                   • Repeat step 7 until you have added a total of 1,000 g.

2. RP9 - Light (reflection and refraction)

   • Method
     • Set up a ray box, slit and lens so that a narrow ray of light is produced.
       • Place a 30 centimetre (cm) ruler near the middle of a piece of plain A3 paper. Draw a straight line parallel to its longer sides. Use a protractor to draw a second line at right angles to this line. Label this line with an ‘N’ for ‘normal’.
         • Place the longest side of a rectangular glass block or acrylic polymer block against the first line. With the normal near the middle of the block, carefully draw around the block without moving it.
           • Use the ray box to shine a ray of light at the point where the normal meets the block. This is the incident ray.
             • The angle between the normal and the incident ray is called the angle of incidence. Move the ray box or paper to change the angle of incidence. Suggested values are 20°, 40°, 60° and 80°.
               • The aim is to see a clear ray reflected from the surface of the block and another clear ray leaving the opposite face of the block.
                 • Using a pencil on the paper, mark the path of:
                   • the incident ray with a cross
                     • the reflected ray with a cross
                       • the ray that leaves the block with two crosses – one near the block and the other further away
                         • Remove the block. Join the crosses to show the paths of the light rays. Measure the angle of incidence, angle of refraction and angle of reflection for each block.
                           • Repeat steps 7 to 8 for an each value of incident angle.

3. RP8 - Acceleration

   • Method
     • Position an air track on a bench with a bench pulley at one end and two light gates above the track. Cut an interrupt card to a known length (such as 10 cm) and attach it to an air track glider.
       • Connect the glider to a hanging mass by a string the length of the air track passing over the bench pulley. Make sure the air track is level and that the card will pass through both gates before the mass strikes the floor.
         • Set the data logging software to calculate acceleration.
           • Add 5 × 20 g slotted masses (0.98 N of force) to the end of the string.
             • Release the glider, then record the weight and acceleration.
               • Repeat steps 4 and 5 two more times, and calculate a mean value for the acceleration.
                 • Repeat steps 4 to 6, removing one of the slotted masses each time (giving forces of 0.78 N, 0.59 N, 0.39 N and 0.20 N.

4. RP8 - Waves (measuring water waves and waves of a string)

   • Method
     • Set up the ripple tank as shown in the diagram with about 5 cm depth of water.
       • Adjust the height of the wooden rod so that it just touches the surface of the water.
         • Switch on the lamp and motor and adjust until low frequency waves can be clearly observed.
           • Measure the length of a number of waves then divide by the number of waves to record wavelength. It may be more practical to take a photograph of the card with the ruler and take measurements from the still picture.
             • Count the number of waves passing a point in ten seconds then divide by ten to record frequency.
               • Calculate the speed of the waves using: wave speed = frequency × wavelength.

5. RP10 - Radiation and absorption (Leslie cube)

   • Method
     • Place a Leslie cube on a heat-resistant mat. Fill it, almost to the top, with boiling water and replace the lid.
       • Leave for one minute. This is to enable the surfaces to heat up to the temperature of the water.
         • Use the infrared detector to measure the intensity of infrared radiation emitted from each surface, or the temperature of the surface. Make sure that the detector is the same distance from each surface for each reading.

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