The Technician exam does not require a large mathematics toolkit.
The useful approach is to keep a small set of relationships clear enough that you can recognize what a question is asking and calculate without guessing.
Start with the four quantities
| Quantity | Common symbol | Unit |
|---|---|---|
| Voltage / electrical potential difference | E | volt (V) |
| Current | I | ampere (A) |
| Resistance | R | ohm (Ω) |
| Power | P | watt (W) |
Learn the quantities before reaching for a formula.
Ohm’s Law
The three useful forms are:
E = I × R
I = E / R
R = E / I
Examples from the study material:
- 12 V with 4 A gives 3 ohms of resistance.
- 120 V across 80 ohms gives 1.5 A of current.
A simple physical check helps: with the same resistance, more voltage should produce more current; with the same voltage, more resistance should reduce current.
DC electrical power
Use:
P = E × I
Rearrange it when the unknown changes:
I = P / E
E = P / I
Examples:
- 13.8 V at 10 A = 138 W
- a 12 V load using 120 W draws 10 A
Wavelength in meters
For a quick free-space estimate:
wavelength in meters ≈ 300 / frequency in MHz
At 146 MHz:
300 / 146 ≈ 2.05 meters
That is also a useful reminder of why the 144–148 MHz amateur band is commonly called the 2-meter band.
Metric-prefix conversions
Keep the powers of one thousand visible:
- giga = 10⁹
- mega = 10⁶
- kilo = 10³
- base unit = 10⁰
- milli = 10⁻³
- micro = 10⁻⁶
- nano = 10⁻⁹
- pico = 10⁻¹²
Examples from the Technician material:
- 1.5 A = 1500 mA
- 1,500,000 Hz = 1.5 MHz
- 500 mW = 0.5 W
Write the starting and finishing units before moving the decimal.
Decibel power-ratio anchors
The exam material uses a few high-value landmarks:
- +3 dB ≈ twice the power
- +6 dB ≈ four times the power
- +10 dB = ten times the power
- -6 dB ≈ one-quarter the power
For example, increasing from 20 W to 200 W is a +10 dB change because the power increased by a factor of ten.
A six-step calculation routine
When a calculation question appears:
- write the quantity being asked for;
- write the unit you need;
- choose the relationship;
- convert prefixes before calculating if necessary;
- substitute the values with their units;
- ask whether the result is sensible.
This catches many errors caused by using the right numbers with the wrong relationship or by overlooking milli-, kilo-, or mega-.
Do not let math crowd out the rest of the blueprint
Electrical principles account for four questions on a normal Technician exam, but the test still draws one question from every official group.
Use the formulas as a compact tool, then return to the wider 35-group exam blueprint.