Page 49 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Technology

What is inductive

wireless charging? How to rid our homes of

messy plugs and cables

f you have ever had to wrestle with a messy electronics could be made small enough to make your device takes longer to charge. It also
tangle of cables, then the introduction of wireless charging feasible for devices such as requires your device to be very close to the

I wireless phone charging will come as a artificial hearts and electric toothbrushes. charger to work, so it effectively still tethers it to
welcome relief – but this useful technology isn’t These days, the inductive charging method a power source just like a cable charger.
actually all that new. Physicist Nikola Tesla fi rst can be used for smartphones, tablets and even However, this could change with a new
concluded that you could transfer power electric cars, but if it’s so convenient, why aren’t method called inductive wireless charging that
between two objects via an electromagnetic fi eld we using it all the time? One reason is that it isn’t is in development and will enable power to be
in the late 1800s, and by the 1990s wires and very efficient, as a lot of energy is lost as heat – so transferred over greater distances.

4 Receiver
How inductive wireless 5 Direct current The magnetic field generates an
The alternating current fl owing

charging works through the receiver coil is then electric current within the receiver
coil of a device when it comes
converted into direct current by
the receiver circuit. within a close distance.
Find out how an electric current can
be sent through the air
6 Battery power
The direct current,
which goes in one
direction, can then be
used to charge the
battery of the device.
3 Magnetic field
As the alternating
current fl ows through
the transmitter coil it
creates a changing
magnetic fi eld.

1 Power source 2 Transmitter
The power coming The current is sent
from the plug sockets to the transmitter
in your walls is Illustration by Adrian Mann circuit in the
alternating current, wireless charger,
which changes which then sends it
direction several to a transmitter
times a second. coil of wire.

How do erasers work? Some erasers contain
pieces of the volcanic rock
pumice to make them
more abrasive
Why we no longer use bread to rub out our mistakes

o understand how erasers remove pencil In fact, anything stickier than paper can be
marks, we first need to know a bit about used as an eraser, and until the 1770s, moist

Tthe pencil itself. Contrary to popular bread was most people’s material of choice.
belief, pencils are no longer made from lead; Reportedly, when scientist Joseph Priestly
instead they consist of a mixture of graphite (a accidentally picked up a piece of latex instead of
soft mineral made up of a crystalline form of bread, he discovered this new substance could
carbon) and clay. also rub out pencil marks, which is where the
When you write on a piece of paper, fl akes of name ‘rubber’ originated from.
this mixture cling to the paper fi bres, leaving Nowadays, because natural latex rubber is
visible marks. Erasers are able to remove these expensive and some people are allergic to it,
marks simply by being stickier than the paper erasers are typically made from synthetic

fibres, so the graphite and clay particles cling to petroleum-based rubbers, for example
the eraser instead. polyvinyl chloride.

How It Works 49