FOCUS ON MATH
Signed Numbers
To solve problems in electrical
and electronic engineering signed numbers
and zeros are needed.
- Numbers preceded by a +
sign are called positive
numbers
- Numbers preceded by a –
sign are called negative numbers
- If the number has no sign
before it, it has an implied +
sign and is a positive number
In electric circuits, you may notice
two kinds of voltages or numbers:
- The positive numbers
measure the voltage above the zero
- The negative numbers measure
the voltage below the zero
Therefore, zero is a reference
point from which positive numbers are greater
and negative numbers are less. Zero
is neither positive nor negative.
Fractions
A fraction means division. The bar is a
sign of grouping for the numerator and the
denominator. We have learned it about the
series circuit. An important characteristic
is that the circuit current i
is the same throughout the entire series
circuit. According to series circuit in
Figure 9.1, the current is determined by
applying Ohm’s law on the entire circuit.
Since the current is constant
in a series circuit, and equation may be
written using the fraction of vs
/RT
. The current i
may be calculated also by applying
Ohm’s law to each resistance in the
circuit of same Figure 7.4 using the fraction
to each element.
|
