Transcript P3 3.2 Electromagnetic induction

1) Explain what an ultrasound wave is (2
marks)
2) Ultrasound waves can be used to clean
jewellery. One method is to put the jewellery in
a bath of cleaning fluid which contains an
electronic oscillator. The electronic oscillator
generates ultrasound waves in the cleaning
fluid. Suggest how these waves clean the
jewellery (2 marks)
1) Explain what an ultrasound wave is (2
marks)
• sound / mechanical / longitudinal (wave )
(1)
• any one from:
• above 20 000 hertz / 20kHz
• above (human) audible range
• cannot be heard by humans
2) Suggest how these waves clean the jewellery
(2 marks)
• either
• particles / molecules / fluid
• vibrate(s) (1)
• (and) knock particles of dirt off the
• jewellery (1)
• or
• by the process of cavitation (1)
• which breaks up / releases dirt from
• the surface (1)
Electromagnetic induction
L.O.
 Design an alternating current generator.
 Explain how to increase the induced
potential difference in a generator.
Homework due on 11th February:
workbook pages 130 & 131.
Simulation
In the pairs: describe how the electromagnetic
induction takes place and how to increase it.
Key words: magnetic field lines, induced
voltage, alternating current.
How to generate electricity.
Watch clip and fill in gaps in script
Task: design an AC generator
o Make some drawings of your design.
o Explain how an electric potential difference is
induced.
o Consider how you could increase the induced
potential difference.
7.a)
(magnetic) field / lines of force / flux
rotate(s) / move(s) / through / in / cut(s)
the coil (1 mark)
potential difference / p.d. / voltage
induced across the coil (mark)
• 7b)
any one from:
• more powerful / stronger / lighter
magnet
• larger / more / bigger / lighter cups /
with a bigger surface area
• longer arms
• lubricate the spindle
• add more turns to the coil
1. (a) (i)
(electromagnetic) induction (1)
1(ii)
swings to the left (1)
1(iii)
no (induced) current (1)
6a)
increase the current (1)
increase the magnetic field (strength) (1)
6b)
o either reverse polarity or connect the battery
the other way round. (1)
o either reverse direction of the magnetic
field or put the magnet the other way round
/ reverse the magnet (1)
Electromagnetic induction
L.O.
 Design an alternating current generator.
 Explain how to increase the induced
potential difference in a generator.
Electromagnetic Induction
Electromagnetic Induction
Electromagnetic Induction
Electromagnetic Induction
Increasing the voltage
How to generate electricity clip
Task:
Workbook pages 130-131.