Keywords: IGCSE Prescribed Practical, Radioactivity, Geiger-Muller Tube, Physics, Radioactive Decay, Radioactive Source, Count Rate, Half-Life, Background Radiation, Ionizing Radiation

Introduction: In this IGCSE Prescribed Practical experiment, we will measure the activity of a radioactive source using a Geiger-Muller (GM) tube. Radioactivity is the spontaneous emission of ionizing radiation from unstable atomic nuclei. Understanding radioactivity and how to measure it is essential for various applications in physics, medicine, and engineering, as well as ensuring safety when working with radioactive materials.

Equipment Needed:

• Geiger-Muller tube
• Radioactive source
• Timer or stopwatch
• Retort stand
• Clamp
• Ruler
• Lead shielding (optional)

Method:

• Set up the Geiger-Muller tube on the retort stand using a clamp, ensuring that the tube is facing the radioactive source.
• Place the radioactive source at a fixed distance from the GM tube, ensuring that the distance is measured from the center of the source to the front of the tube.
• Switch on the GM tube and allow it to warm up for about 30 seconds.
• Record the background radiation by counting the number of clicks or beeps from the GM tube over a specific time interval (e.g., one minute) without the presence of the radioactive source.
• This step is crucial for obtaining accurate results, as it accounts for the natural radiation in the environment.
• Place the radioactive source in front of the GM tube at the previously measured distance.
• Start the timer or stopwatch and record the number of clicks or beeps from the GM tube over the same time interval used for measuring background radiation.
• Subtract the background radiation count from the count obtained with the radioactive source to obtain the net count rate.
• Repeat steps 5-7 at least three times to obtain an average net count rate for increased accuracy.

Expected Findings and Calculations: The net count rate obtained from the experiment represents the activity of the radioactive source, measured in counts per minute (cpm) or counts per second (cps). This measurement is important for determining the intensity of ionizing radiation emitted by the source and evaluating its potential hazards.

Conclusion: By performing this IGCSE Prescribed Practical experiment, you will learn how to measure the activity of a radioactive source using a Geiger-Muller tube. Understanding radioactivity and its measurement is crucial for various applications in physics, medicine, and engineering, as well as ensuring safety when working with radioactive materials.

Questions:

1. What is radioactivity?
2. What is the purpose of the Geiger-Muller tube in this experiment?
3. Why is it important to measure background radiation?
4. How do you calculate the net count rate?
5. What are some applications of radioactivity measurements in real life?

Answers:

1. Radioactivity is the spontaneous emission of ionizing radiation from unstable atomic nuclei.
2. The Geiger-Muller tube is used to detect and measure ionizing radiation emitted by the radioactive source.
3. Measuring background radiation is important for obtaining accurate results, as it accounts for the natural radiation in the environment, which can affect the measurements.
4. The net count rate is calculated by subtracting the background radiation count from the count obtained with the radioactive source.
5. Radioactivity measurements have various applications, including medical imaging and treatments, nuclear power generation, research in physics, and ensuring safety when working with radioactive materials.

• Practical Physics