Biomedical Engineering Reference
In-Depth Information
Table 1.3
Derives quantity and Unit
Quantity
Symbol
Expressed in terms
of SI base units
Unit
Unit symbol
T
-1
Frequency
F
Hertz
Hz
Ms
-1
Velocity
V
Meter per second
m/s
mm
-1
s
-1
= s
-1
Angular velocity
x
Radian per second
Rad/s
m s
-2
m/s
2
Acceleration
A
Meter per second square
mm
-1
s
-2
= s
-2
Rad/s
2
Angular acceleration
Radian per second square
m kg s
-2
N (kg/m/s
2
)
Force
F
Newton
m
-1
kg s
-2
N/m
2
Pressure
p
Newton Per meter Square
m
2
kg s
-2
Energy
W
Joule
J (Nm)
Charge
Q
s A
Coloumb
S/A
m
2
kg s
-3
A
-1
Potential difference
V
Volt
V (W/A)
m kg s
-3
A
-1
Electric field strength
E
Volt per meter
V/m
m
2
kg s
-2
A
-1
Magnetic flux
f
Weber
Wb
kg s
-2
A
-1
(wb/m
2
)
Magnetic flux density
B
Tesla
m
-2
lm/m
2
Luminance
L
cd
Lux
M
2
kg s
-3
A
-2
Electric resistance
X
ohm
V/A
m
-2
kg
-1
s
4
A
2
Capacitance
F
Farad
C/V
m
-2
kg
-1
s
3
A
2
Electric conductance
S
Siemens
A/V
m
2
kg s
-2
A
-2
Inductance
H
Henry
Wb/A
m m
-1
Phase angle
r
Radian
1
Table 1.4
Decimal multiples and sub-multiples
Prefix
Multiple
Symbol
Example
10
-18
Atto
a
1 am (size of electrons)
10
-15
Femto
f
Diameter of proton
10
-12
Pico
p
10 pF (capacitance)
10
-9
Nano
n
1,000 pF (capacitance)
10
-6
Micro
l
1 lF (capacitance)
10
-3
Mili
m
mm (100 mm-diameter)
10
-2
Centi
c
cm (1 cm distance)
10
-1
Deci
dB
Audio level
10
1
Deca
dc
Audiologist(decagram)
10
2
Hecto
h
Hectoliter (bulk liquid), hectometer (radio band)
10
3
Kilo
k
100 kg (weight/mass)
10
6
Mega
M
100 MHz (frequency value)
10
9
Giga
G
100 GB (hard disk capacity)
10
12
tera
T
1 TB (hard disk capacity)
1.5 Classification of Measurement
The classification is important in understanding how different measurement sys-
tems work and comparing their performance later on. The benefits of classification
are obvious in many walks of life. The animal kingdom, for example, is classified
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