Communication satellite failed to reach geostationary orbit

This video shows a European Space Agency Ariane rocket that was launched earlier this week.  The rocket was carrying two satellites intended for geostationary orbit, the W3B satellite for French company Eutelsat and a satellite for Japanese company B-SAT corporation, called BSAT-3b.

There’s lot of information in the clip.  The commentator tells viewers about the liquid rocket fuels (hydrogen and oxygen), the water dousing system used at liftoff and explains each stage of the rocket’s journey presentation.

The French W3B satellite was designed to provide TV, radio and internet services to Europe, Africa and the Middle East.  At 13:11 in the film, we can see the release of W3B.  Notice that the left side of the screen shows an altitude of only 1,200km at this point. This is not high enough to achieve geostationary orbit and the satellite must use its own propulsion system to reach an altitude of 36,oookm.

Unfortunately, W3B experienced propulsion problems and was unable to climb to 36,000km.  There is a BBC news report of the mission failure here.  The photograph in the BBC article is particularly good because, although the satellite is wrapped in protective film, we can clearly see two curved reflectors wrapped in silver film.

S3 telecommunications hw for 3.3 & 3.4

Hello S3!

Here is your homework exercise on telecommunications.  I would like you to put the answers to each of these questions in your blue homework jotter and hand it in to me no later than Tuesday 14th September.  You will not receive credit for doing the homework if your jotter is handed in after this deadline.

Use the calendar on the right to check for any important dates (HW deadlines, assessments, parent evenings) during your Standard Grade course.  There is a podcast button under the calendar that will help you to subscribe to all future hw and answers on iTunes.  Just ask if you need help with that.

S3 how a TV works – part 3

The site I have been using throughout the television section of the course is here.

The shadow mask makes sure that electrons fired from the filament responsible for each colour of sub-pixel do not hit the wrong phosphor dots, e.g. electrons sent by the “green” gun do not reach the phosphor dots that glow red or blue.  This animation shows how the shadow mask works.

S3 how a TV works – part 1

Here is a short video clip showing how an image can be built up on a TV screen, one line at a time.  In a real TV set, the beam moves much more quickly (about 7000 m/s!) across the screen and 25 complete images are shown each second.

raster scan from mr mackenzie on Vimeo.

Remember that in a real TV set, the beam does not scan its way back up the screen but takes a “flyback” from the bottom right to the top left corner to start on the next image.

Finding the distance to a thunderstorm

The thunderstorm this morning reminded me that I was going to post something about calculating the distance to a storm.

Play this video and then replay it, paying close attention to the time index at the bottom.  You will need to move your cursor over the video box to keep the time visible.

Lightning from Daniel Dingemanse on Vimeo.

Can you calculate the distance between the flash of lightning and the camera?

Hint: take the speed of sound in air as 340 m/s.

total internal reflection

By coincidence (pardon the pun!), both Int2 and S3 have reached the stage of investigating total internal reflection at the same time.  Here is a photo showing total internal reflection of a laser beam in a tank of water.

I’ve put together a short video showing total internal reflection in a semicircular block and a perspex model of an optical fibre.

total internal reflection from mr mackenzie on Vimeo.

inside a tv set

We spent the last lesson of this term taking an old colour television apart. Even if you didn’t have the screwdriver, you were able to see the whole thing close up thanks to Ellie’s webcam and the digital projector.  I have edited down the footage to around 2.5 minutes of TV destruction and added some still shots as well.

inside a tv set from mr mackenzie on Vimeo.

Can you use your knowledge of how a tv works to identify some of the parts as they are removed from the box?  Leave a comment to tell me what you noticed.  I’ll keep them secret until after the holidays so everyone gets a chance to reply.  You can download a smaller version of the video from iTunes.

P.S.  As we are now in the Easter holidays, I have left you an Easter egg. Who will be the first to find it?