Page 102 - Concise Encyclopedia of Robotics

Electrochemical Power
Photovoltaic cell
Energy
beam
Lens
Power Laser diode Actuating Lens
supply circuit
Controlled
device

Electric eye

this voltage or current change. Using amplifiers, even the smallest change
can be used to control large machines.
Electric eyes do not always operate with visible light. Infrared (IR),
with a wavelength somewhat longer than visible red, is commonly used
in optical sensing devices. This is ideal for use in burglar alarms, because
an intruder cannot see the beam, and therefore cannot avoid it.
ELECTROCHEMICAL POWER
An electrochemical cell is a unit source of direct-current (DC) power.When
two or more such cells are connected in series to increase the voltage, the
result is a battery. Electrochemical cells and batteries are extensively used
in mobile robots.
Lead–acid cell
Figure 1 shows an example of a lead–acid cell. An electrode of lead and an
electrode of lead dioxide, immersed in a sulfuric acid solution, exhibit a
potential difference. This voltage can drive a current through a load. The
maximum available current depends on the volume and mass of the cell.
If this cell is connected to a load for a long time, the current will grad-
ually decrease, and the electrodes will become coated. The nature of the
acid will change. All the potential energy in the acid will be converted
into DC electrical energy, and ultimately into heat, visible light, radio
waves, sound, or mechanical motion.

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