Electricity Fundamentals

Define electrical current and describe what it represents in a circuit.
Explain Ohm’s Law and provide its formula.
If a device has a resistance of 4 ohms and is connected to a 12-volt power supply, what is the current through the device? Show your calculation.
Describe voltage and its role in an electrical circuit.
What are the units for voltage, current, and resistance, and what symbols represent each in equations?
Explain the difference between direct current (DC) and alternating current (AC).
What device would you use to measure resistance, and how does it work in a simple explanation?

Electrical Power and Resistance

If a light bulb uses 2A of current on a 120V supply, calculate the power consumption of the light bulb.
Define electrical power and explain its relationship to current and voltage. Provide the formula.
Describe what happens to resistance in a conductor as its temperature increases, and give an example of where this might be important in an electronic device.
In a parallel circuit with two resistors of 10 ohms each, what is the total resistance?

Define frequency and explain what it measures in the context of waves.
If a wave has a frequency of 100 MHz, calculate its approximate wavelength in meters.
What is the relationship between wavelength and frequency, and why does it matter in radio communication?
What is meant by the term wavelength in the context of electromagnetic waves?
If the frequency of a wave increases, what happens to its wavelength? Explain why.

Describe the HF (High Frequency) band range and mention one reason why it’s used for long-distance radio communication.
At what frequency range would you find the VHF (Very High Frequency) band, and what types of communication commonly occur there?
Why is it important for an antenna length to match the wavelength or a fraction of the wavelength of the frequency being used?
If you have an antenna that is 1/4 the wavelength of a 144 MHz signal, calculate its length.