Here is a link to some revision notes for the Our Dynamic Universe unit.

# Higher

## introducing special relativity…

We’ve been looking at Einstein’s special theory of relativity this week. Special relativity is tricky get get your head round. Let’s start with a video about the speed of light.

We watched this video in class, it follows Einstein’s thought process as he worked through his special theory of relativity.

**time dilation**and

**length contraction**. We’ll look at time dilation first.

###
**time dilation**

another take on special relativity and the twins paradox

…and the Glesga Physics version

**length contraction**

This video has helpful examples to explain length contraction.

Sometimes it’s easier to imagine we’re a stationary observer watching a fast moving object go whizzing past. For other situations, it’s better to put yourself into the same frame of reference as the moving object, so that ** everything else** appears to be moving quickly, while you sit still. The muon example in this video shows how an alternative perspective can work to our advantage in special relativity.

Another way to think about this alternative frame of reference is that it’s hard to measure distances when you yourself are moving really quickly. Think about it, you’d get tangled up in your measuring tape like an Andrex puppy.

###### image: trotonline.co.uk

It would be far easier to imagine you’re the one sitting still and all the objects are moving relative to your position, as if your train is stationary and it’s everything outside that’s moving. That keeps everything nice and tidy – including your measuring tape. Got to love Einstein’s postulates of special relativity.

###### image: mirror.co.uk

## H tension HW answers

I’ve marked your HW jotters and will hand them back during tomorrow’s lesson.

I’ll go over the main issues in class but many of you need to review the way you attempt tension questions; use a free body diagram and only use F=ma when you know the resultant force. These two videos should help.

HW question 4 from mr mackenzie on Vimeo.

Higher HW Q5 from mr mackenzie on Vimeo.

## higher homework

Your homework questions are attached. Please return to me by Wednesday 20th September.

## higher ODU revision notes

Here are some notes to help you prepare for the assessment later this week. There are also some useful resources on BBC Bitesize.

## higher assignment

Your assignment will be based on an optoelectronics topic. You will get some ideas for practical work by downloading this booklet.

I have attached a copy of the Scholar notes for unit 3 of the CfE Higher course. You will find background physics with appropriate energy band explanations on pages 103-142.

Don’t print this document, it’s huge!

## 1996 higher paper

Thanks to Mr Ferguson for sharing his copy of the marking instructions for the 1996 Higher paper, it’s the only one I didn’t have! You’ll find a link to his answers on the Higher revision page.

## higher particles and waves revision

Remember that your unit assessment for P&W will take place at the end of this week. The attached notes might be helpful during your revision.

## particle accelerators

An electric field can be used to accelerate charged particles.

Conservation of energy tells us that

*work done by the electric field = change in the particle’s kinetic energy*

The speed of the particle can be determined if its charge and the accelerating voltage (potential difference) are known. The notes attached to the end of this post will show how to perform the calculation.

These short video clips show how to draw electric field lines for point charges and parallel plates, with example calculations for the work done by electric fields and the final speed of charged particles in electric fields.

Q1(a) Electric fields lines around point charges from mr mackenzie on Vimeo.

Q1b – Electric field between parallel plates from mr mackenzie on Vimeo.

Q2 – Work done in moving a charged particle through a potential difference from mr mackenzie on Vimeo.

Q3 – Calculating the speed of a charged particle in an electric field from mr mackenzie on Vimeo.