Physics HL
5
Chapters
329
Notes
Theme A - Space, Time & Motion
Theme B - The Particulate Nature Of Matter
Theme C - Wave Behaviour
Theme D - Fields
Theme E - Nuclear & Quantum Physics
Physics HL
Theme E - Nuclear & Quantum Physics
Discovering Half-Life: Lab Methods & Radioactive Decay Analysis
667 words
4 mins read
Last edited on 5th Nov 2024
Table of content
Half-life Introduction
- Half-life is the time taken for half the radioactive atoms in a substance to decay.
- Want to measure it? You’ve got a couple of fun tricks up your sleeve!
Measuring Short Half-lives
- 🎨 Graphical Approach: A curve that maps corrected count rate against time. (Fancy, but be careful with how you draw it!)
- 🧠 Smart Graphical Approach: Based on the equation - ln(R) = − λt + ln (R0)
- R: corrected count rate
- R0: initial corrected count rate
- This looks like the equation for a straight line y = mx + c. So, a graph of ln(R) against time (t) gives a straight line!
- 📈 Gradient: −λ
- 📌 Y-intercept: ln (R0)
- Half-life \((T\frac12): - \frac {0.693}{gradient}\)
- Advantage: You can find the half-life even if you measure for a time less than the actual half-life. Clever, right?
Getting Hands-on in the Lab
- Safety First! Always know the ethical, environmental, and safety issues. Don’t want to become a comic book hero just yet!
- Essentials: Geiger–Müller tube (detects radiation) + stopwatch OR a snazzy data logger with a radiation sensor.
- Experiment Steps
- Measure the room's background radiation (like checking the temperature before jumping into a pool).
- Bring the decaying stuff (radioactive material) close to your sensor.
- Monitor the count rate until it's close to the background rate.
- The Corrected Count Rate = Observed count rate - Background count rate.
- Plot that sweet graph of ln(corrected count rate)ln(corrected count rate) against time.
- Compare your value with the accepted half-life. Feels good when it matches, right?
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Physics HL
Theme E - Nuclear & Quantum Physics
Discovering Half-Life: Lab Methods & Radioactive Decay Analysis
667 words
4 mins read
Last edited on 5th Nov 2024
Table of content
Half-life Introduction
- Half-life is the time taken for half the radioactive atoms in a substance to decay.
- Want to measure it? You’ve got a couple of fun tricks up your sleeve!
Measuring Short Half-lives
- 🎨 Graphical Approach: A curve that maps corrected count rate against time. (Fancy, but be careful with how you draw it!)
- 🧠 Smart Graphical Approach: Based on the equation - ln(R) = − λt + ln (R0)
- R: corrected count rate
- R0: initial corrected count rate
- This looks like the equation for a straight line y = mx + c. So, a graph of ln(R) against time (t) gives a straight line!
- 📈 Gradient: −λ
- 📌 Y-intercept: ln (R0)
- Half-life \((T\frac12): - \frac {0.693}{gradient}\)
- Advantage: You can find the half-life even if you measure for a time less than the actual half-life. Clever, right?
Getting Hands-on in the Lab
- Safety First! Always know the ethical, environmental, and safety issues. Don’t want to become a comic book hero just yet!
- Essentials: Geiger–Müller tube (detects radiation) + stopwatch OR a snazzy data logger with a radiation sensor.
- Experiment Steps
- Measure the room's background radiation (like checking the temperature before jumping into a pool).
- Bring the decaying stuff (radioactive material) close to your sensor.
- Monitor the count rate until it's close to the background rate.
- The Corrected Count Rate = Observed count rate - Background count rate.
- Plot that sweet graph of ln(corrected count rate)ln(corrected count rate) against time.
- Compare your value with the accepted half-life. Feels good when it matches, right?
Unlock the Full Content!
Dive deeper and gain exclusive access to premium files of Physics HL. Subscribe now and get closer to that 45 🌟
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