Posterous theme by Cory Watilo

3.6

·         3.6 use the relationship between frequency and time period:

      frequency =        1                 f = 1       

                        time period               T

f = 1/T

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

T = period (the time for one cycle) (s)

<<f=1overT.ppt>>

<<f=1overT drag and drop questions.swf>>

Click here to download:
f=1overT.ppt (221 KB)
(download)

(download)

3.2

·         3.2 describe longitudinal and transverse waves in ropes, springs and water where appropriate

Transverse Waves

·        

<<transverse wave - perpendicular motion.swf>>

Longitudinal Waves

·          

<<longitudinal waves - same direction of motion.swf>>

 

 

3.2 Practicals

10 February 2011

14:44

Practicals:

·         Make a transverse wave on a rope

·         Make a longitudinal wave on a rope

(commendations available for anyone who can do this!)

·         Make a transverse wave on a slinky spring

·         Make a longitudinal wave on a slinky spring

·         Observe a transverse wave on a ripple tank

 

 

3.2 Plenary Answers 1

10 February 2011

14:44

Answers

 

Transverse

Longitudinal

Radio

Sound

Microwaves

Spring

Infrared

 

Light

 

Ultraviolet

 

X-rays

 

Gamma rays

 

Water

 

Rope

 

Spring

 

 

 

3.2 Plenary Answers 2

10 February 2011

14:44

PFY p.178

Image001

(download)

(download)

 

 

2.19

24 November 2010

10:32

·         2.19 recall that:

·         voltage is the energy transferred per unit charge passed

·         the volt is a joule per coulomb.

V = E/Q or E = Q.V

V = Voltage (V)

E = Energy (J)

Q = Charge (C)

 

Therefore 1V = 1J/C

 

 

2.19 Top Tips for Calculations

24 November 2010

10:32

Top Tips for Calculations

(The bold writing is what you write down)

1.              Write down what the question tells you.  I = 4A, t = 20s

2.              Write down what the question asks you for.  Q = ?

3.              Find an equation that links all these variable. 

Formula  Q = I.t                    (1 mark)

4.              Substitution  Q = 4 x 20        (1 mark)

5.              Answer and Units Q = 80C     (1 mark)

 

 

2.17 and 2.19 Plenary worksheet

15 December 2011

09:30

<<Q=It and V=EoverQ worksheet.doc>>

Image001

Click here to download:
Q=It and V=EoverQ worksheet.doc (57 KB)
(download)

 

 

2.17

24 November 2010

10:31

·         2.17 recall and use the relationship between charge, current and time:

        charge = current × time     

               Q = I × t

Q = I.t

Q = Charge (C, Coulomb)

I = Current (A)

t = time (s)

 

How to remember this formula…

"If the exam is hard, don't ever Q(u)It"

 

 

2.16

24 November 2010

10:31

·         2.16 understand that current is the rate of flow of charge

Demo

·         Ball of aluminium foil swinging between two metal plates which are charged by Wimshurst generator

·        

 

 

2.18 answers

24 November 2010

10:32

·         2.18 recall that electric current in solid metallic conductors is a flow of negatively charged electrons

Conventional  Current

·         The flow of "imaginary" positive charges from + to -

·         Why?  Positive charges are repelled by the positive terminal of the battery and attracted to the negative terminal of the battery

·         Symbol "I"

·         Used in 90% of exam questions!

 

 

I

I

I

0image001

Flow of Electrons

·         The flow of real negatively charged electrons from - to +

·         Why?  Negative electrons are repelled by the negative terminal of the battery and attracted to the positive terminal of the battery

 

Image002

2.11 Exam style question - model answer

2.11 Exam style question - model answer

26 November 2010

12:43
[cid:image001.jpg@01CCD50F.43F028A0]
· Explain the shape of the V-I graph for a filament lamp with reference to the movement of electrons in the tungsten wire and the temperature of the wire (3 marks)
[cid:image002.png@01CCD50F.43F028A0]

(download)

2.14

2.14

24 November 2010

10:16
· 2.14 know that lamps and LEDs can be used to indicate the presence of a current in a circuit
>

Crocodile technology
· Drag file 6 (attached) into the Croc clips window and it will open (you might have to save this file to your desktop first)
· Push the push switches on each of the 4 circuits
· Can you explain what you see?

2.14 answers

24 November 2010

10:16

Filament lamps
· Turn on when a current flows either way through them
· You can see that their V/I graph is symmetrical - they behave the same with positive and negative voltages

[cid:image001.jpg@01CCD50B.40EAD4B0]

Light Emitting Diodes (LEDs)
· Turn on when a current flows "forwards" through them (in the direction of the arrow)
· You can see that their V/I graph is asymmetric - they behave differently with positive and negative voltages
· Diodes are like a one way door that
o allows current to flow when a positive voltage is applied
o does not allow current to flow when a negative voltage is applied

[cid:image002.png@01CCD50B.40EAD4B0]

Click here to download:
6 LEDs vs lamps.cyt (7 KB)

(download)

2.13 plenary MABA

2.13 plenary MABA

24 November 2010

10:15
· 2.13 describe the qualitative variation of resistance of LDRs with illumination and of thermistors with temperature

LDR


Light


Dark (4 letters)


Resistance (high/low)


Low


High (4 letters)


Thermistor


Hot (3 letters)


Cold (4 letters)


Resistance (high/low)


Low (3 letters)


High (4 letters)

2.13 practical

2.13 practical

24 November 2010

10:15
· 2.13 describe the qualitative variation of resistance of LDRs with illumination and of thermistors with temperature
· Select the 20kΩ range on the multimeter
· Connect an LDR to the multimeter
· Use your thumb to cover the LDR
· Connect a thermistor to the multimeter
· Rub the thermistor between your finger and thumb to warm it up
· Fill in the following results tables

LDR


Light


Dark


Resistance (kΩ)


Resistance (high/low)


Thermistor


Hot


Cold


Resistance (kΩ)


Resistance (high/low)