Tuesday, 28 February 2012
Wednesday, 22 February 2012
7.9
7.9
12 January 2012
10:24
· 7.9 recall the sources of background radiation
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Whys Guy
· http://youtu.be/CUqdLwIITWM
7.4 and 7.5
7.4 and 7.5 starter 
01 February 2012
10:00
Tell the person next to you…
· What are the 7 parts of the electromagnetic spectrum you learnt in P3, Waves?
· What are they in order of increasing frequency?
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(Note that microwaves are missing from this animation!)
Answers
· Radio waves
· Microwaves
3. Infra Red
4. Visible
5. Ultra violet
6. X-Rays
7. Gamma Rays
7.4 and 7.5
12 January 2012
10:24
· 7.4 understand that alpha and beta particles and gamma rays are ionising radiations emitted from unstable nuclei in a random process
· 7.5 describe the nature of alpha and beta particles and gamma rays and recall that they may be distinguished in terms of penetrating power
Producing Alpha, Beta and Gamma radiation
· http://youtu.be/pHUgL_RS9ng
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Penetrating Power
· http://www.youtube.com/watch?v=48JQaZHuFsQ&feature=youtu.be
· http://youtu.be/61y2GTr0MlQ
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Ionisation
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Effect of magnetic and electric fields
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7.8
7.8
12 January 2012
10:24
· 7.8 understand that ionising radiations can be detected using a photographic film or a Geiger-Muller detector
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7.3
7.3
12 January 2012
10:24
· 7.3 understand the terms atomic (proton) number, mass (nucleon) number and isotope
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PhET animation - build an atom
31 January 2012
13:34
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Website
http://phet.colorado.edu/en/simulation/build-an-atom
Embed code for your blog
| Click to Run |
PhET animation - isotopes
31 January 2012
13:34
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Website
http://phet.colorado.edu/en/simulation/isotopes-and-atomic-mass
Embed code for your blog
| Click to Run |
7.2
7.2 starter
31 January 2012
11:35
Tell the person next to you…
· The names of 3 subatomic particles
· What properties do they have?
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7.2
11 January 2012
14:49
· 7.2 describe the structure of an atom in terms of protons, neutrons and electrons and use symbols such as 146C to describe particular nuclei
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P7 Keywords - First Homework
Homework for next Wednesday
P7 Keywords - First Homework
02 September 2010
18:41
Step 1 = Unscramble the Keywords and Mixed Definitions sheet.
4 options:
· Kinaesthetic Learners = Cut and Stick into your exercise book. Take a photo of your work and send to your blog
· Kinaesthetic Learners = Cut and Paste in the Word document and send to your blog
· Visual Learners = Copy out into your exercise book. Take a photo of your work and send to your blog
· Visual Learners = Type out and send to your blog
Step 2 = Check your keywords by using one of the following online games. Make corrections to your work in a different coloured pen/font so that you can see your mistakes clearly.
· http://www.patana.ac.th/LearningObjects/%7BFC7DE36D-42FC-47FC-B072-2E4EA5DFDB...
· http://www.patana.ac.th/LearningObjects/%7BD0CC1663-8A7B-4215-B618-A645F8A399...
· http://www.patana.ac.th/LearningObjects/%7BE40854B9-2D1A-4ECA-B286-6B70310AD2...
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Sunday, 12 February 2012
6.19 and 6.20 Plenary answers
6.19 and 6.20 Plenary answers
01 December 2011
18:08
[cid:image001.png@01CCE7CB.95BA8CB0]
a. Vs/Vp=ns/np
Vs/2=80/20
Vs=8V
b. Vs/Vp=ns/np
Vs/10=20/100
Vs=2V
c. Vs/Vp=ns/np
Vs/240=20/400
Vs=12V
d. Vs/Vp=Ns/Np
Vs/4=2000/50
Vs=160V
[cid:image002.jpg@01CCE7CB.95BA8CB0]
2. Vs/Vp=ns/np
3/24=ns/480
ns=60turns
[cid:image003.jpg@01CCE7CB.95BA8CB0]
a. Iron (Why? Iron is a magnetically soft material - it can be magnetised and lose its magnetism easily. This is necessary in a transformer as the magnetic field needs to change repeatedly)
b. electrical energy in the primary coil => magnetic energy in the core =>electrical energy in the secondary coil
c. dc current produces a steady magnetic field in the core. To induce a current in the secondary coils there must be a changing magnetic field in the core.
[cid:image004.jpg@01CCE7CB.95BA8CB0]
a. Step down (because the voltage decreases)
b. Vs/Vp=ns/np
12/240=ns/1000
ns=50turns
c. P = V x I
24 = 12 x I
I = 2A
d. Power in secondary = 24W
e. Power in primary = 24W
f. P = V x I
24 = 240 x I
I = 0.1A
g. The current would be greater/double
Why?
Efficiency = Useful Pout/Total Pinx100
50 = 24/Total Pin x 100
Total Pin = 48W
P = V x I
48 = 240 x I
I = 0.2A
Plenary questions
6.18 Plenary Multichoice questions
01 December 2011
18:13
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6d Plenary answers
[cid:image001.png@01CCE7CD.E0122820]
[cid:image002.png@01CCE7CD.E0122820]
[cid:image003.jpg@01CCE7CD.E0122820]
a.deflection to the left
b. deflection to the left
c. no deflection
1. push the magnet in quicker
2. use a coil with more turns
3. use a stronger magnet
P6 Plenary: 10 multi-choice questions
14 December 2011
12:49
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Friday, 3 February 2012
6.17
6.17
01 December 2011
18:08
· 6.17 recall the structure of a transformer, and understand that a transformer changes the size of an alternating voltage by having different numbers of turns on the input and output sides
6.17 Practical - model answers
17 January 2012
14:33
· If you…
· Turn the powerpack to dc
[cid:image001.jpg@01CCE252.359BA450]
No current is induced in the Secondary Coil. To induce current you need a changing magnetic field and this is not produced by applying dc to the Primary Coil
· Turn the powerpack to ac
[cid:image002.jpg@01CCE252.359BA450]
ac is induced in the Secondary Coil. To induce current you need a changing magnetic field and this is produced by applying ac to the Primary Coil
3. Increase the number of turns in the Secondary Coil
The size of the induced voltage in the secondary coils increases
4. Increase the voltage on the Primary Coil
[cid:image003.jpg@01CCE252.359BA450]
The size of the induced voltage in the secondary coils increases
5. Decrease the number of turns in the Secondary Coil
The size of the induced voltage in the secondary coils decreases
6. Decrease the voltage on the Primary Coil
The size of the induced voltage in the secondary coils decreases
6.20
6.20 
01 December 2011
18:08
· 6.20 recall and use the relationship (for 100% efficiency):
input power = output power
Vp Ip = Vs Is
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6.19 and 6.20 Plenary
01 December 2011
18:08
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[cid:image001.png@01CCE252.4D9BE600]
6.19
6.19
01 December 2011
18:08
· 6.19 recall and use the relationship between input (primary) and output (secondary) voltages and the turns ratio for a transformer:
input (primary) voltage = primary turns
output (secondary) voltage secondary turns
Vp/Vs = np/ns
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6.18
6.18
01 December 2011
18:08
· 6.18 explain the use of step-up and step-down transformers in the large-scale generation and transmission of electrical energy
· http://youtu.be/LZKhGGBcYFI
6.16
6.16
01 December 2011
18:08
· 6.16 describe the generation of electricity by the rotation of a magnet within a coil of wire and of a coil of wire within a magnetic field; also describe the factors which affect the size of the induced voltage
· Magnet rotating near coil
[cid:image001.png@01CCE252.2901EF10]
· Coil rotating near magnet
[cid:image002.jpg@01CCE252.2901EF10]
· ac generator
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[cid:image003.jpg@01CCE252.2901EF10]
6.16 Practical - model answers
17 January 2012
14:33
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· Connect a hand turned generator to a light bulb. Observe the light bulb when you...
· Rotate the generator slowly
The induced voltage decreases
· Rotate the generator quickly
The induced voltage increases
3. Increase the strength of the magnet
The induced voltage increases
4. Increase the number of turns in the coil
The induced voltage increases
6.16 Plenary
17 January 2012
15:20
· What are the 3 ways that you can increase the size of the current induced in a generator?
Answers
· Increase the strength of the magnets
· Increase the speed of the relative motion
· Use a coil with more turns of wire
Faraday's Lab animation
Faraday's Lab animation
28 November 2011
15:06
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Website:
http://phet.colorado.edu/en/simulation/faraday
6.16 generator simulation
28 November 2011
15:06
Website:
6.15
6.15 starter
01 December 2011
18:08
· What’s the motor effect?
· "If there’s a magnetic field perpendicular to a current in a wire, the wire moves in a direction perpendicular to the field and the current" (FLHR)
· So what about if we move a wire in a magnetic field? What happens in the wire?
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· When we move a wire in a magnetic field, a current is induced in the wire
6.15
01 December 2011
18:08
· 6.15 recall that a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it; also recall the factors which affect the size of the induced voltage
[cid:image001.png@01CCE252.11AB81F0]
[cid:image002.jpg@01CCE252.11AB81F0]
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6.15 Practical - model answers
17 January 2012
14:33
· If you...
· Push the North pole of the magnet into the coil
A negative current flow shown by a negative deflection on the ammeter
· Keep the magnet stationary within the coil
No current
3. Pull the North pole of the magnet out of the coil
A positive current
4. Push the South pole of the magnet into the coil
A positive current
5. Push the North pole of the magnet slowly into the coil
A smaller negative current
6. Push the North pole of the magnet quickly into the coil
A larger negative current
7. Change the coil for one with more turns of wire and push the North pole of the magnet into the coil
A larger negative current
8. Push the North pole of a neodymium (strong) magnet into the coil
A larger negative current
9. Move the magnet in and out of the coil repeatedly. What sort of current is this?
An alternating current
6.15 Plenary answers
16 January 2012
· Explain carefully how you can induce a current in a wire (3 marks)
· State 3 ways you can increase the size of this induced current (3 marks)
Answers
· The wire must be perpendicular to a magnetic field
· The wire and magnetic field must move relative to each other – the wire must “cut” through the magnetic field lines/lines of magnetic flux as it moves
· A current is induced in the wire. The induced current is perpendicular to both the field and the motion
· Increase the strength of the magnets
· Increase the speed of the relative motion
· Use a coil of wire instead of a single piece of wire
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