Teaching Science » Sc4

Physics Powerpoints

Danny Nicholson — Tue, 16 Dec 2008 10:57:06 +0000

The Institute of Physics has produced some useful KS2 PowerPoint presentations which you can use to introduce different physics concepts to your class.

As well as PowerPoints there are suggested activities that you can try out.

You can access the resources here. Click on each topic to see the resources available.

Circuits

Danny Nicholson — Thu, 19 Jun 2008 12:55:47 +0000

To answer another one of the questions you submitted. Trying to explain why the brightness of bulbs in a circuit changes can be tricky. It can be helpful to imagine different analogies/models to explain what is happening.

A very nice place to start is this presentation from Skool.co.uk

A battery with one bulb connected is your standard to compare things to. Electricity flows from one end of the battery to the other, flowing through the bulb as it goes, making the bulb light up.

Adding a second bulb in series will increase the total resistance in the circuit. The bulbs will be dimmer than the single bulb.

Adding a second bulb in parallel is a different situation. You have added a second parthway for the electricity to flow, The resistance is greater than a single bulb, but is is not as high as the two bulbs in parallel. The two bulbs will be brighter.

A “cars on the highway” analogy may help explain the distinction: think of a wide highway narrowing to a one-lane bridge to cross a river. Now imagine that in order to get rid of traffic jams, the highway department builds another one-lane bridge over the river. The “resistance” (in this case analogous to the width), of both bridges stays the same, but the amount of “current” or traffic that can cross the river has increased, so the overall “resistance” of the entire system has decreased. Taken from here.

In a series circuit, each bulb you add will make the brightness of the bulbs dimmer and dimmer

In a parallel circuit, the brightness of the bulbs does not change with the addition of more bulbs (but if you added many parallel circuits, eventually all of the bulbs would dim down as you approached the capacity of the battery)

This page from the BBC KS2 Bitesize site is pretty useful.

The GCSE Bitesize page may help explain things to you too.

Link to other Links Pages

E=TC3 6G Changing Circuits Page

E=TC3 4f Circuits and Conductors Page

TopicBox – Electricity

Day, Night, Seasons

dannynic — Sun, 01 Jun 2008 08:41:46 +0000

Another one of your questions was about Day, Night and Seasons. I’ll try and link to some good animations and guides about this that are already on the web.

The Earth is always lit from one side by the Sun. The side that is in shadow is in Nighttime, the side that is lit by the Sun is in Daytime. If you follow one spot on the Earth such as London, as the Earth spins it will eventually move from night into day and then later back into night time again. From where we are standing it looks like it is the Sun that’s moving instead.

You can see what the view from space above London is like right now with this viewer.

You can see what’s happening on this animation

http://www.childrensuniversity.manchester.ac.uk/interactives/science/earthandbeyond/dayandnight.asp

To add to the confusion: The Earth is slightly tilted on its axis. This means at some times of the year, the Northern Hemisphere is tilted slightly towards the Sun (Summer) and at other times of the year it is tilted away from the Sun (Winter). At the Spring and Autumn Equinox the two hemispheres are neither tilted away or towards the sun.

There are some more diagrams on this page which illustrate this.

Here’s a nice animation of the Earth going around the Sun, showing the effect of the tilt on the seasons.

http://mesoscale.agron.iastate.edu/agron206/animations/01_EarthSun.html

The tilt also affects the length of a day on Earth. You can explore that with this animation

http://www.childrensuniversity.manchester.ac.uk/interactives/science/earthandbeyond/sunrisesunset.asp

In the winter the Sun rises later and sets earlier. We have short days and long nights. In the Summer the sun rises earlier and sets later, we have long days and shorter nights. At the Spring and Autumn equinox the length of day and night is equal (equi = equal nox=night)

More Info

http://www.bbc.co.uk/science/space/solarsystem/earth/solsticescience.shtml

http://www.boutichesaid.cv.dz/Earth/EarthLight/EarthLight.htm

http://en.wikipedia.org/wiki/Seasons

http://www.badastronomy.com/bad/misc/seasons.html

http://www.fourmilab.ch/earthview/vplanet.html

http://www.bbc.co.uk/schools/ks2bitesize/science/revision_bites/earth_sun_moon.shtml

World Wide Telescope

dannynic — Tue, 27 May 2008 07:52:01 +0000

Microsoft have finally released the public beta of their World Wide Telescope project, and I just had to write about it. It’s a must for anyone who has to teach about space, or just anyone interested in astronomy.

Basically, its Microsoft’s version of Google Earth/ Google Sky and if you’ve used the Google version in the past then you’ll pick this up very easily.

The software provides a virtual planetarium and lets you study the night sky with great detail. Some of the images are astounding. You can also switch the view to study planets and moons such as Jupiter and Io.

When looking at the stars, right clicking will bring up a star identifier which tells you the name of the star (if known) and some information about it. You can even link direct to the relevant wikipedia page.

Maybe a quick activity would be to search for their star sign (I looked up Aries) and find the names of the stars in the constellation. Maybe even find out how far away they are from Earth.

You can also point the camera downwards and study the Earth instead just like Google Earth, although not in as high resolution. A nice feature is the Earth at Night view which shows just where all the populated areas are. Interesting to use for Geography perhaps?

This is highly recommended and would be an excellent piece of software for anyone who has to teach about the Earth and space. Download it from here.

Why can’t we see the dark side of the moon?

dannynic — Sun, 18 May 2008 10:08:37 +0000

Firstly, it’s had to google this without getting lots of hits for classic Pink Floyd albums. Secondly, strictly speaking it’s the *far* side of the moon. It’s not always dark because sometimes it is facing directly at the Sun and is well lit.

Anyway, the question relates to the fact that Moon always keeps the same face facing towards the Earth (and so the same face pointing away). This down to two important facts.

1. The moon rotates on its on axis, it takes approximately 28 days to make one full rotation

2. The moon orbits around the earth. It takes approximately 28 days to make one full orbit.

In the animation below, I have coloured the moon to make it clearer. This is the view from above as it rotates.

View Full Screen

As the moon rotates, it is also travelling around the Earth. The Moon has become locked into a pattern – the time it takes to orbit the Earth is the same as the time it takes to make one full rotation – approximately 28 days.

View Full Screen

As you can see, as the moon travels around the Earth, it is also rotating. The Red/Yellow face is always kept facing towards the Earth. If we were standing on the Earth looking at the Moon we would only see the Red/Yellow face. We would never be able to see the Blue/Green face.

Other Animations

http://www.edumedia-sciences.com/a213_l2-earth-moon-system-1.html

More Moon Information

Mundesley School Space Page

Hammer and Feather Drop

Danny Nicholson — Thu, 15 May 2008 07:13:24 +0000

What happens when you drop a heavy object and a light object at the same time? Well they should hit the ground at exactly the same time. This is because the pull of gravity is the same on each one, and so they accelerate at the same rate.

On Earth it’s hard to visualise this since air resistance also gets involved – and so if you drop a hammer and a feather the feather floats down slower than the hammer.

On the moon, there is no air, so air resistance does not affect the result. One of the experiments carried out by the Apollo astronauts on the moon was to demonstrate a hammer and feather drop and as you can see, without air resistance both the hammer and feather hit the ground at the same time.