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JC2 T2W8 HBL
JC2 T2W8 HBL
Step 1:
Read the following parts to learn more about:
Detection of radiation particles via a Cloud Chamber
Radiation safety
Some A-level questions pose extension questions beyond mere calculations on such topics above!
1. Cloud Chamber
Particle detectors that count particles, like Geiger-Muller (GM) tubes (which your tutor will show you in our physics lab!), are useful but they cannot distinguish different types of particle.
What is a cloud chamber?
The cloud chamber is one of the earliest particle detectors ever created. It was invented by Scottish Physicist, Charles Wilson, who was attempting to study cloud formation when he discovered that he’d accidentally invented a particle detector! He perfected the first
(expansion) cloud chamber in 1911 and
received the Nobel Prize in 1927. Cloud chambers detect charged subatomic particles, like muons, electrons, and alpha particles.
(Watch the video on the right)
How does it work?
(Watch the next Youtube video below).
The space inside the chamber is filled with alcohol vapour and, as a particle passes through, tiny droplets of alcohol form, showing up its track. It’s a bit like the vapour trails you see when a jet aircraft flies through the high, cold atmosphere. Radiation particles will lose energy as they interact with air molecules.
Types of tracks produced and why?
As you watch the video, think about:
1) Why are ionising radiation the ones that mainly produce tracks
2) Why are the tracks for alpha and beta particles different?
Types of tracks produced and why?
The following table explains the shape of tracks for each type of radiation particle:
Alpha particles have a high ionizing ability so a large number of atoms is ionized along its trajectory leading to the particle being slowed down very quickly. This leads to wide and short straight tracks due to the relatively high mass of the particle.
Beta particles/ electrons have a lower ionizing ability which leads to long thin tracks which are not straight due to the relatively low mass.
2. Radiation Safety:
The Radiation Protection and Nuclear Science Group (RPNSG) is the national authority for radiation protection in Singapore! It administers and enforces the Radiation Protection Act and Regulations through a system of licensing, notification, authorisation, inspection, and enforcement.
The key functions of RPNSG are listed as follows:
Administer and enforce the Radiation Protection Act (RPA) and its Regulations;
License the import, export, sale, possession, use and transport of radioactive materials and irradiating apparatus;
Ensure the safe use of ionising and non-ionising radiation;
Monitor radiation dose exposure for radiation workers;
Provide radiation-related and consultancy services (e.g. calibration of survey meters and radioactivity testing);
Control the disposal of radioactive waste;
Implement international conventions relating to nuclear safety, security and safeguards that Singapore is a party to;
Jointly respond with Singapore Civil Defence Force to radiological emergencies.
Environmental Radiation Monitoring:
Singapore monittors the 24-hour mean ambient Gamma Dose Rate here.
What is radioactive waste and how are they stored?
(Watch the next Youtube videos below).
High-level wastes are hazardous because they produce fatal radiation doses during short periods of direct exposure.
Nuclear power plants store spent nuclear fuel in "spent fuel pools" made of reinforced concrete several feet thick, with steel liners. The water in the pools is typically about 40 feet deep and serves both to shield the radiation and cool the rods.
Step 2:
Attempt the following exit quiz by clicking here
JC1 T3W9 HBL
JC1 T3W9 HBL
Today, you gain an admission ticket into our 'Physics Wonderland' (see below), where you will spend the next few hours learning Physics!
Please arm yourself with the Work Energy Power lecture notes and a bottle of water as you go along.
With your new-found knowledge of WEP, complete tutorial questions Q1 - Q9. Your tutor will then go through Q5, Q8, Q9 answers only in the next f2f tutorial.
If the above does not load, please go to this link. You can soften the volume if it's too distracting!
Answers to Lecture Examples:
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