Monday, 24 June 2013

Gowth Mindset

Fostering a growth mindset in learners (children, adults) may be one of the key to improve learner's motivation to learn, ownership of learning, perseverance, etc.  As teachers, we may not have been tackling the root cause of these learning characteristics.

Learners will benefit greatly from a changed mindset about learning.

The benefits of a Growth Mindset - Carol Dweck

 The Power of Belief - Mindset and Success: Eduardo Briceno at TEDxManhattanBeach

Friday, 21 June 2013

Physics of Haze

I couldn't help it but to apply what I know in Physics to explain the white/gray haze as a result of the smoke particles from the Sumatran fires.

To begin, let's try to understand how we see the colours of the buildings and the trees. We "see" the colour of the light that is scattered off the surface of the building, leaves, etc, as shown.
Scattering of light from surface (e.g. green wavelength em waves from the leaves) causes us to "see" the objects' colour

Light is also scattered by the air molecules (~ nanometer in diameter) along the path from the sun to the object by a process known as Rayleigh Scattering (refer to my previous post) towards the observer. However intensity from this scattering is low compare to the intensity of light reaching the objects and scattering to the observer. Generally our eyes cannot sense this low intensity in the presence of the light from the objects.
Effect of Rayleigh Scattering is small and hence don't produce the white haze 

With the dust particles, diameter in the region of microns (0.000001 m), suspended in the air, Mie scattering dominates. The scattering intensity by this process is larger than Rayleigh Scattering. The larger intensity of white light scattered from these particles (consisting of all visible wavelengths) is now more obvious to us.
Mie Scattering off the dust particles produces the white haze seen the above photo
The additional scattering also explain why the sky and the sun appears red around 6 pm, something we usually observe around 7pm when the sun is close to the horizon.
Red sky and sun around 6pm

For more information on the different type of scattering, you may want to refer to this.

Thursday, 20 June 2013

Using Tracker to study solar spectrum (with absorption lines) for the topic of Quantum Physics

Line Spectral with Tracker
Created this instructional video on "using Tracker for spectroscopy". Youtube link is here.

Lessons that took place before this activity Students could have
  • observed the emission spectrum of elements such as sodium, neon, mercury, kryption, etc. although they do not have hands-on experience of setting up and adjusting the apparatus.
  • gone through the theory and tutorial on the section of spectral lines.
Below is the worksheet that students will attempt.

Pictures of the solar spectrum and the emission spectrum of different elements (derived from the picture here and here).
Disadvantages of hands-on approach
  • Experiments on spectral lines are time consuming due to the difficulty in setting up and calibrating the spectrometer.
  • The other big challenge is the availability of a suitably dark room to observe the emission spectrum of discharge tubes.
  • The availability of sufficient apparatus for experiments.
Advantages of using Tracker
  • Cheap.
  • Easy to deploy.
  • Easy to operate to obtain quality results for comparison and analysis because students  can now focus on the actual physics rather than on the setting up of the experiment.

What is a Field?

This is the Physicists' way of looking at the field concept. Kind of difficult for layman like us to understand. Enjoy :-)

From Scientific American