Thursday, 9 July 2015

Day 5 - Thursday 9th July (Theoretical Examination and Sanjay Gandhi National Park)

Today the students undertook their second (and final) competitive task of the week – the theoretical examination that was ratified in Wednesday’s international board meeting. The theoretical examination is comprised of three questions (which have multiple subsections) and lasts five hours.

The Sun imaged in extreme UV
(Source 1)
The first question asked the students to consider how we can determine information about a star from the particles emitted from it. Students began by using information about photons (particles of electromagnetic radiation, i.e. light) to determine some information about the Sun (such as its surface temperature), how we can capture the Sun’s energy using solar cells and then, by using the Kelvin Helmholtz hypothesis, estimate how long the Sun has been emitting electromagnetic radiation for. Following this, the students then considered other subatomic particles (called neutrinos) to prove that the Sun has nuclear fusion occurring in its core and to make further calculations, including an estimate of the temperature of the core of the Sun.

Refraction of light through glass
(Source 2) 
The second question was about a concept called the ‘extremum principle’, which the students first applied to moving objects to derive various equations to explain the object’s motion. Secondly, the extremum principle was then applied to optics to determine equations that are common to the study of refraction. Thirdly, the extremism principle was applied to the work by de Broglie to consider the wave nature of matter, such electrons (particles) demonstrating diffraction (classically considered to be a wave phenomenon).

Tarapur Nuclear Reactors 3 & 4
(Source 3)
The third question was inspired by India’s nuclear energy programme, specifically the Tarapur 3 and 4 nuclear reactors in Thane, West India, to consider the nuclear fission process (i.e. splitting of atomic nuclei) and structural design of a nuclear reactor. The students were required to make calculations about the nuclear fuel pins, the neutron moderator and the reactor itself. This question paid homage to the Department of Atomic Energy, who have been instrumental in supporting the organisation and hosting of this year’s IPhO in India.

Monkeys (rhesus macaque) in the SGNP
Meanwhile, the team leaders, observers and visitors went on an excursion to the Sanjay Gandhi National Park (SGNP) to see the Kanheri caves and its surrounding wildlife (including many monkeys). There is a stark contrast between the 104 square kilometres of forest and hills that make up the park and the vast surrounding city of Mumbai and its suburbs that is home to roughly 20 million inhabitants.

Kanheri caves in the SGNP
The Kanheri caves are a number of Buddhist settlements excavated into the basalt rock from around the 4 century BC. This visit is was another reminder of the vibrant religious diversity of India, which include significant numbers of people practising Hinduism, Islam, Sikh, Buddhism, Christianity and Jainism, as well as having smaller numbers practising Parsi and Judaism. In fact, with India’s national population of around 1.3 billion citizens, India has the second largest Muslim population in the world (after Indonesia) - contributing around 11% of the total practising Muslims across the globe.

The day finished off with students and team leaders meeting up for dinner and discussions of the week so far, as all examinations have now taken place. The UK team were in good spirits, enthusiastically discussing both examinations as well as their impressions of India and how they have particularly enjoyed spending time with students from the other countries at the 2015 IPhO.

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