higher assignment video – earthquakes

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We’re going to start the researching physics unit and assignment next week.  Before we go to the computer room, please watch the attached video so you will have some ideas about the science of earthquakes and how they can be detected.

This is a large video file – make sure you are connected to wifi before downloading.  

Please do not stream the video as this will prevent others from viewing at the same time.  Download the file before you start to watch.

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refraction, critical angle and total internal reflection

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We met refraction during the National 5 course.  At Higher level, we are interested in the relationship between the angles of incidence θi and refraction θr.

Snell’s law tells us that

n_1\sin \theta_i = n_2 \sin \theta_r

Usually material 1 is air, and so n_1 = 1.  This simplifies Snell’s law to

\sin \theta_i = n \sin \theta_r

where n is the absolute refractive index of material 2.  Since the refractive index is equal to the ratio of the ray’s speed v in materials 1 & 2 and also equal to the ratio of the wave’s wavelength λ in materials 1 & 2, we can show that

n = \displaystyle {{{\sin \theta_i} \over  {\sin \theta_r}}} = \displaystyle {v_1 \over v_2} = \displaystyle {\lambda_1 \over \lambda_2}

Read more about Snells’s law here.

total internal reflection

total internal reflection from mr mackenzie on Vimeo.
The critical angle \theta_c and refractive index n are related by

\sin \theta_c = \displaystyle {1 \over n }

Here are some applications of total internal reflection here.  You can test your knowledge of refraction with this interactive simulation.

I have attached a pdf with some notes and questions on refraction, total internal reflection and critical angle.

Read

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national 5 assignment – part 2

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The second programme is all about the current state of car safety.

We follow a car safety team at Volvo as they prepare to crash two cars together to collect forces data, learn how emergency medicine procedures are changing to improve outcomes for car accident casualties, and learn how sensors are used to monitor the human body’s response to a collision.

Please watch both programmes before Thursday 18th February.

As with the first video, please check you are connected to wifi before downloading as the video file is quite big.

Podcast: Play in new window | Download

national 5 assignment – part 1

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We’re going to start work on the assignment task next week.  You’ll spend 2-3 periods researching car safety online and choosing a particular topic to explore in more depth.  Before we go into the ICT room, I’d like you to watch two videos about car safety.

The first programme looks back at the history of car accidents and the work that has been done to reduce deaths on the road.  While many of the clips shown are quite old, they show just how far we have come in our understanding of the science behind making cars more safe.

Please right click on the link below and save your own copy of the file, rather than streaming it.

Check you’re using wifi before downloading – it’s a big file!

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diffraction

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Diffraction of a red Laser beam with a diffraction grating

red laser beam passing through a diffraction grating. image: en.academic.ru

Diffraction is a test for wave behaviour.  When a ray of light passes through a diffraction grating, the energy of the incident beam is split into a series of interference fringes.  Constructive interference is occurring at each location where a fringe (or spot) is observed because the rays are in phase when they arrive at these points.

diffraction spots projected on to a wall

image: microscopy uk

Find out about diffraction gratings here.

image: laserpointerforums.com

We can measure the relative positions of the fringes in a diffraction pattern to determine the wavelength of the light used.  The diffraction grating equation is

m \lambda = d \sin \theta

where

  • m is the diffracted order  –  some resources may use n instead of m
  • λ is the wavelength
  • d is the line spacing.

Here is an infrared diffraction experiment you can try at home to calculate the wavelength of the infrared LED in a remote control.

I’ve attached a set of pdf notes and questions on diffraction.  These notes use n rather than m for the diffracted order.

Read

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the photoelectric effect

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We learned about the photoelectric effect this week.  This video has a similar demonstration to the gold leaf electroscope experiment I showed you in class and includes an explanation of the process.

httpv://www.youtube.com/watch?v=RR4T1IlM2Jw

Click on the picture below to download the simulation we used to investigate the effect of irradiance on frequency on photocurrent.  You’ll be prompted to install Java if you don’t have it already.

Once the animation is running, you can;

  • change the metal under investigation (we used zinc in class)
  • vary the wavelength of the incident light
  • vary the irradiance of the incident light.

Notice that below the threshold frequency you can’t get any photoelectrons, even if you set the light to its brightest setting.

Compare your results to the graphs provided in your notes.

I have attached some notes & questions on the photoelectric effect. Click on the link below to download a copy.

Read

E-Book PDF: Open in New Window | Download