Posterous theme by Cory Watilo

Homework for next Tuesday

1.    4.6 to 4.8 Reading from Pearson.  Note down 5 key facts from the text in your exercise books as 5 bullet points – I will check these at the beginning of next lesson.  Stuck?  Use Objectives 4.6 to 4.8 to guide you as to what you need to know.

2.    Rate yourself using A/T/W/U against objectives 4.6 to 4.8 in the “End of lesson” column

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4.6 to 4.8 Reading from Pearson

10 May 2012

14:41

(download)

 

 

4.2 to 4.5 Plenary Answers, Pearson p.132

10 May 2012

08:54

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b.

Efficiency = Useful Eout / Total Ein x 100

Efficiency = 350 / 400 x 100

Efficiency = 88%

 

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a.               It is transferred to thermal and sound energy

 

 

4.2 to 4.5 Plenary Questions, Pearson p.132

10 May 2012

08:54

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4.5

10 June 2011

11:42

·         4.5 describe a variety of everyday and scientific devices and situations, explaining the fate of the input energy in terms of the above relationship (see 4.4), including their representation by Sankey diagrams

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4.5 plenary questions and answers

10 June 2011

11:42

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Answers

 

Kettle

10 squares = 2000J/s therefore 1 square = 200J/s

Wasted Heat = 2 squares = 400J/s

Useful Heat = 5 squares = 1000J/s

Wasted sound = 3 squares = 600J/s

 

Efficiency = Useful Eout / Total Ein x 100

Efficiency = 1000 / 2000 x 100

Efficiency = 50%

 

Computer

Conservation of energy so…

Total Ein = Total Eout

150J = 20 + 10 + Useful Eout

Useful Eout = 120J/s

 

Efficiency = Useful Eout / Total Ein x 100

Efficiency = 120 / 150 x 100

Efficiency = 80%

 

 

4.4

10 June 2011

11:42

·         4.4 know and use the relationship:

                             efficiency = Useful Eout / Total Ein

Version 1

 

Efficiency = Useful Eout / Total Ein x 100

 

Useful Eout = useful energy output (J)

Total Ein = total energy input (J)

Efficiency = Efficiency (%)

 

Version 2

 

Efficiency = Useful Eout / Total Ein

 

Useful Eout = useful energy output (J)

Total Ein = total energy input (J)

Efficiency = Efficiency (no units; a number between 0 and 1)

 

 

4.4 Plenary questions

10 June 2011

11:42

<<Efficiency.ppt>>

Click here to download:
Efficiency.ppt (214 KB)
(download)

 

 

4.4 starter

10 June 2011

11:42

<<% efficiency energy.swf>>

(download)

 

 

4.3

10 June 2011

11:42

•        4.3 understand that energy is conserved

<<Energy input; energy output worksheets.pdf>>

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Example answer

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Click here to download:
Energy input; energy output worksheets.pdf (311 KB)
(download)

 

 

4.2 starter

10 June 2011

15:32

Tell the person next to you…

1.             What are the 9 types of energy?

(Note: "solar", "wind", etc are NOT types of energy - they are energy resources!)

Do you know your formulae?

 

Do you know your formulae?

28 February 2011

07:14

Unit 3 Formulae

 

Tell the person next to you…

·         All of the formulae from this unit

o    eg. "The formula that links v, f and λ is…"

·         All of the quantities from this unit

o    eg. "λ = Wavelength"

·         All of the units from this unit

o    eg. "The unit of wavelength is metres"

Answers

 

Formulae

 

·         v = f x λ

·         f = 1/T

·         n = sin i / sin r

·         sin c = 1/n

·         v = d / t

 

Quantities and Units

 

·         v = wave speed (m/s)

·         f = frequency (Hertz, Hz)

·         λ = wavelength (m)

·         T = period (s)

·         n = refractive index (no units)

·         i = angle of incidence (o)

·         r = angle of refraction (o)

·         c = critical angle (o)

·         d = distance (m)

·         t = time (s)

3.25

 

 

3.25

10 February 2011

14:49

·         3.25 describe how digital signals can carry more information

 

 

Vinyl LP record - old school!

DVD

 

 

 

 

(download)

3.23

3.23

10 February 2011

14:56

·         3.23 understand the difference between analogue and digital signals

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·         Analogue signals vary continuously

·         Digital signals are discrete - they are either 1 (on) or 0 (off)

·         Data stored as a stream of 1s and 0s is called "binary code"

 

 

3.20

10 February 2011

14:56

·         3.20 describe the role of total internal reflection in transmitting information along optical fibres and in prisms

 

 

<<Total internal reflection.mpg>>

 

TIR

Optical fibres

 

<<TIR demo and uses of - interactive.swf>>

Applications of TIR using prisms

Periscope

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Bicycle reflector

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Binoculars

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Applications of TIR using fibre optics

Endoscope

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Communications networks (telephone and internet)

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(download)

Click here to download:
Plenary Questions.pptx (56 KB)
(download)

 

 

3.21

10 February 2011

14:56

·         3.21 explain the meaning of critical angle c

 

 

·         You should already have learnt this from the keywords from this unit

·         Tell the person next to you the definition now!

 

 

 

 

 

 

 

 

 

 

Answer

·         The smallest angle of incidence for which Total Internal Reflection occurs

also acceptable:

·         The angle of incidence for which the angle of refraction is exactly 90o

 

 

3.22

10 February 2011

14:56

·         3.22 know and use the relationship between critical angle, and refractive index:

              sin c = 1 / n

sin c = 1 / n

 

c = critical angle (o)

n = refractive index (no units)

 

 

3.22 Plenary Answers

09 March 2012

09:46

Answers

Q1.  What is the refractive index of glass that has a critical angle of 42o?

 

sin c = 1/n

sin 42 = 1/n

n = 1/sin 42

n = 1.5

 

Q2.  What is the critical angle for diamond? (ndiamond = 2.4)

 

sin c = 1/n

sin c = 1/2.4

c = sin-1 0.417

c = 25o

(download)

 

 

3.14 to 3.22 Plenary questions, Pearson p.116 and 117

21 March 2012

12:57

(download)

 

 

3.14

10 February 2011

14:45

·         3.14 recall that light waves are transverse waves which can be reflected, refracted and diffracted

 

Watch the demos for...

·         Reflection of a laser in a smoke box

·         Refraction of a laser in a smoke box

·         Diffraction of a laser by a human hair

 

 

3.10 to 3.13 Plenary Answers

01 April 2011

16:09

<<Answers to Everything I need to know about the EM Spectrum.doc>>

(download)

 

 

3.15 practical

10 February 2011

14:56

<<Investigating reflection expt worksheet.doc>>

 

 

3.15

10 February 2011

14:56

·         3.15 recall that the angle of incidence equals the angle of reflection

Reflection, i=r

<<Obj 3.15.ppt>>

<<animated law of reflection.swf>>

 

 

3.15 plenary

10 February 2011

14:56

<<reflection game.swf>>

(download)

Click here to download:
Obj 3.15.ppt (287 KB)
(download)

Click here to download:
Investigating reflection expt worksheet.doc (151 KB)
(download)

(download)

 

 

3.16

10 February 2011

14:56

·         3.16 construct ray diagrams to illustrate the formation of a virtual image in a plane mirror

<<Obj 3.16.ppt>>

Reflection – virtual image

 

 

3.16 Plenary Answers

10 February 2011

14:56

For plane mirrors, the image is…

·         The same size as the object

·         The same distance as the object from the mirror

·         Virtual (not real)

·         Upright

·         Laterally Inverted

Task 1 Answers

 

For plane mirrors, the image is…

·         The same size as the object

·         The same distance as the object from the mirror

·         Virtual (not real)

·         Upright

·         Laterally Inverted

 

 

3.15 and 3.16 Plenary Multiple Choice Questions

21 April 2011

09:44

<<Plenary Questions.ppt>>

Click here to download:
Plenary Questions.ppt (166 KB)
(download)

Click here to download:
Obj 3.16.ppt (306 KB)
(download)

 

 

3.9

10 February 2011

14:52

·         3.9 understand that waves can be diffracted through gaps, and that the extent of diffraction depends on the wavelength and the physical dimension of the gap

 

Diffraction by a gap

·         Most of the wave passes straight through the gap

·         But the sea wall causes diffraction at the edges of the wave

·         Note that the wavelength is the same before and after diffraction

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·         Diffraction is at a maximum when the width of the gap is equal to the wavelength of the wave

·         The plane waves are now completely curved

·         Note that the wavelength is the same before and after diffraction

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Website http://www.falstad.com/ripple/

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Diffraction patterns in the sea

 

 

 

3.9 Plenary Answers

10 February 2011

14:52

PFY p.178 Q.2

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(download)

 

 

3.8

10 February 2011

14:52

·         3.8 understand that waves can be diffracted when they pass an edge

 

Website http://www.falstad.com/ripple/

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3.10 and 3.11 starter

27 February 2012

15:17

·         Do you know the 7 colours of the visible spectrum?

·         Can you put them in order from longest to shortest wavelength?

Answer

1.            Red (longest wavelength)

2.            Orange

3.            Yellow

4.            Green

5.            Blue

6.            Indigo

7.            Violet (shortest wavelength)

 

How can you remember the order?

Richard Of York Gave Battle In Vain!

 

 

3.10 and 3.11 starter 2

27 February 2012

15:17

·         Do you know the 7 parts of the EM spectrum?

·         Can you put them in order from longest to shortest wavelength?

Answer

1.              Radio (longest wavelength)

2.              Microwaves

3.              Infrared

4.              Visible

5.              Ultraviolet

6.              X-rays

7.              Gamma rays (shortest wavelength)

 

Can you make a mnemonic to help you remember the order?

by Remembering Mnemonics I ...

 

 

3.10 and 3.11

10 February 2011

14:44

·         3.10 understand that light is part of a continuous electromagnetic spectrum which includes radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray radiations and that all these waves travel at the same speed in free space

·         3.11 recall the order of the electromagnetic spectrum in decreasing wavelength and increasing frequency, including the colours of the visible spectrum

EM Spectrum – speed, wavelength and frequencies

<<EMFlash[1].swf>>

 

 

3.10 and 3.11 plenary

10 February 2011

3.5

3.5 recall and use the relationship between the speed, frequency and wavelength of a wave:          

    wave speed = frequency × wavelength           

                   v = f × λ

 

 

<<Waves - Tr Lo WL f A.mpg>>

<<Longitudinal wave, wavelength. v = f x lambda.mpg>>

 

v = f λ

v = wave speed (m/s)

f = frequency (Hz) or (cycles/s)

λ = wavelength (m)

 

1,000 Hz = 1 kHz 

1000,000 Hz = 1,000 kHz = 1 MHz

 

 

3.5 Plenary

10 February 2011

14:52

·         What happens to the wavelength if you increase the frequency of the wave but keep the wave speed the same?

·         What happens to the wavelength if you decrease the frequency of the wave but keep the wave speed the same?

·         Verify your answers by using http://www.falstad.com/ripple/

 

Super tough extension task

·         Try changing the speed in the simulation.  Does that do what you expect?  Explain.

Answers

v = f λ

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Increases

v = f λ

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Decreases

Super tough extension task

·         Try changing the speed in the simulation.  Does that do what you expect?  Explain.

·         The slider just changes the "simulation speed" NOT the "wave speed"!

 

 

virtual ripple tank

11 January 2011

15:12

Link to animation

http://www.falstad.com/ripple/

 

Embed code for your blog

(download)

Answers to PFY p.178

 

3.7 Answers

10 February 2011

14:52

PFY p.178 Answers

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v = f λ

v = 170 x 2

v = 340m/s

 

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v = f λ

v = 200,000 x 1,500

v = 300,000,000m/s

 

v = f λ

300,000,000 = 500,000 x λ

λ = 600m

 

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f = 1 / T

2 = 1 / T

T = 0.5s

 

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·         5 complete cycles of the wave measures 10cm

·         So each cycles measures 10cm/5 = 2cm

·         Therefore λ = 2cm or 0.02m

 

v = f λ

6cm/s = f x 2cm

f = 3Hz