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Microwaves
Mobile phones send out microwave
signals. These are low power microwaves,
and are used to cook some foods.
Microwaves cannot go through metal, but
they can go through glass and plastic.
A microwave and an oven have a metal
grid to reflect the microwaves back, and to
heat up the food.…read more

Slide 3

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How are Microwaves and ovens
different?
When microwave radiation is Conventional ovens use infrared
absorbed by water, the water radiation. Lots of infrared is emitted
heats up. The Microwaves emit by hot surfaces and more infrared
about 1cm into the food, is emitted and absorbed by black
increasing their kinetic energy. surfaces. Infrared radiation is
The heat energy is then absorbed by all the particles in the
conducted to the cool food from food, increasing their kinetic
its hot interior. energy.…read more

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Can you find it?
What kind of
I A G I R E A L D M radiation is emitted
by ovens?
U N F W A C O I E E
What are
Q B F E D V E F T T microwaves and
infrared types of?
E H D R I H J E C A
Microwaves emit
R A Q U A R P S U L about 1cm into the
food, increasing
L P Z A T R L F D M their _______
energy.
S A Y B I C E U N A
Microwaves cannot
A T M U O X K D O N go through ______
In microwave ovens
S I K I N E T I C P the energy is then
D X G J U O Z K G L _______ from the
surface to the centre
of the food…read more

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Energy given out
High amount of
energy given out.
Laser
Medium amount of
energy given out.
Infrared
Low amount of
energy given out.
Microwave…read more

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Diffraction
Diffraction and
and Interference
Interference
Diffraction and
interference can
cause the signal
given out by the
waves to be
weakened. This is
why transmitters
need to be high
above ground, to
prevent obstacles
getting in the way
of the signal.…read more

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