Electricity Fundamentals

Define electrical current and describe what it represents in a circuit.
Draw a simple electrical circuit that includes a lamp, battery and switch. Include the polarity of the battery and indicate direction of current flow.
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?
Draw the schematic symbols that represent - electric cell, open switch, resistor and lamp.
Describe the prefixes milli(m), kilo (k) and mega (M)

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?

Explain what each symbol (V, I, and R) represents in Ohm's Law.
How would you calculate the current flowing through a resistor if you know the voltage across it and its resistance?
If a circuit has a 12V battery and a 4-ohm resistor, what is the current flowing through the resistor? Show your working.
Describe what happens to the current in a circuit if you increase the resistance while keeping the voltage constant.
How would the voltage change in a circuit if you double the current but keep the resistance the same?

What is the unit for Power?
Define each variable in the power formula.
If a circuit has a voltage of 10V and a current of 2A, what is the power output? Show your calculations.
How would you find the voltage if you know the power and current in a circuit? Give an example.
In a situation where both current and voltage increase, explain how this affects the power in a circuit.
If the power in a circuit is 50W and the current is 5A, what is the voltage? Show your calculation.

Define frequency and explain what it measures in the context of waves.
What are the frequency ranges for MF, HF, VHF and UHF?
What is a pure sine wave?
Draw a sine wave showing the relationship between voltage, wavelength and time.
If a wave has a frequency of 100 MHz, calculate its approximate wavelength in meters. What simple formula can you use?
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.