Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

3.3.3Stoichiometry

Core Practical- Using an Oscilloscope — Cambridge IGCSE Chemistry 0620 Revision Notes & Topical Questions

5 min read 5 parts Lesson 25 of 28 Unit quiz

📚 Cambridge IGCSE Chemistry 0620 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read

Part 1 of 5Variables and Equipment

3.3.3 Core Practical- Using an Oscilloscope
Variables and Equipment
Independent variable
  • The tuning fork used, with each fork producing a different frequency of sound.
Dependent variable
  • The time period of the wave shown on the oscilloscope screen.
Control variables
  • The microphone position and the set-up of the oscilloscope should be kept the same for each tuning fork.
Equipment
  • A tuning fork, a microphone, an oscilloscope and connecting wires.

Part 2 of 5Method

1
Connect the microphone to the oscilloscope and check that it shows a signal by humming into it.
2
Adjust the time base until several complete waves fit across the screen.
3
Strike a tuning fork on a hard surface and hold it close to the microphone so that a pure tone is recorded.
4
Freeze the trace, count the divisions for one complete wave, and repeat the process for each tuning fork.

Part 3 of 5Calculation and Evaluation

Time period
  • Multiply the number of divisions for one cycle by the time base setting, so 4 cm at 1 ms/cm gives 4 ms.
Frequency
  • Convert the time period to seconds and use f = 1 / T, so 4 ms becomes 0.004 s and gives a frequency of 250 Hz.
Systematic error
  • Small time base units such as milliseconds are easy to misread, so the scale must be read and applied correctly.
Random error
  • Background noise adds uncertainty to the trace, so the experiment should be carried out in a quiet room.

Part 4 of 5Worked Example

Question

  • On an oscilloscope, one complete wave covers 5.0 cm and the time base is set to 2 ms/cm.
  • Calculate the time period and the frequency of the sound.

  1. Find the time periodT = 5.0 cm × 2 ms/cm = 10 ms.
  2. Convert to secondsT = 10 ms = 0.010 s.
  3. Calculate the frequencyf = 1 / T = 1 / 0.010 s = 100 Hz.
    What the symbols mean: T = period, the time for one complete wave (s) · f = frequency (Hz)

Answer The time period is 0.010 s and the frequency is 100 Hz.

Part 5 of 5Exam Checklist & Tips

3.3.3 – Key Points for the Exam

  • Time base The horizontal scale setting of an oscilloscope, usually given in milliseconds per centimetre.
  • Tuning fork A metal fork that produces a sound of a single, pure frequency when it is struck.
  • Time period (T) The time for one complete wave to pass a point, measured in seconds.
  • Frequency (f) The number of complete waves per second, measured in hertz.
  • Pure tone A sound with a single frequency, produced by a tuning fork.

Common Mistakes

  • Using the time period in milliseconds directly in f = 1 / T without converting it to seconds.
  • Counting the number of waves on the screen instead of the number of divisions for one complete cycle.
  • Confusing this practical with the speed of sound practical, which uses distance and time.
  • Attempting to find the frequency from the loudness of the trace; frequency comes from the time period.

Last updated:

\n