Introduction to Electronics Lecture

Overview

• Basic components in electronics
• Focus on resistors, light bulbs, LEDs, potentiometers, voltage dividers, and solar cells

Resistors

• Found in almost every electronic circuit
• Limit the amount of current flowing in the circuit
• Ohm's Law:
  • V = I * R
  • V: Voltage (volts)
  • I: Current (amps)
  • R: Resistance (ohms)*

Example Calculations

• 12V Battery with Resistor: Conventional current flows from positive to negative, actual electron flow is opposite
• Current Calculation: I = V / R
  • With 3 ohms resistor: 4 amps
  • With 6 ohms resistor: 2 amps

Concepts

• As resistance increases, current decreases
• Power Rating of Resistor: P = V * I or P = I^2 * R or P = V^2 / R
  • Important to ensure resistor does not burn up

Example: Maximum Voltage Calculation

• Given: 100 ohms resistor, power rating 1/2 watts
• Formula: V = √(P * R)
  • V = √(0.5 * 100) = 7.07V
• Ensure voltage does not exceed this value to prevent overheating

Connecting Resistors

Series Circuit

• Total resistance is the sum of individual resistors
• Only one path for current to flow
• Current through each resistor is the same

Parallel Circuit

• Total resistance is reduced
• Multiple paths for current to flow
• Voltage across each resistor is the same
• Example with two 10 ohm resistors:
  • Series: 10 + 10 = 20 ohms
  • Parallel: 5 ohms (half of value)

Light Bulbs (Incandescence)

• Converts electricity to light energy
• Heats up filament to emit light
• Not energy efficient, generates a lot of heat

LEDs (Light Emitting Diodes)

• More efficient compared to incandescent bulbs
• Monochromatic: Emit light of specific wavelength
• Typical voltage drop: 2V
• Current range: 0.1mA to 20mA
• Current limiting resistor example:
  • With 9V battery, 7V across resistor: R = 7V / 10mA = 700 ohms

Potentiometers

• Variable resistors
• Controls voltage/current in a circuit
• Example: Brightness control with potentiometer and LED
  • Safety resistor required to prevent overcurrent
  • Adjusts current to change LED brightness

Application in Voltage Divider

• Two or more resistors used to reduce voltage
• Incorporating potentiometer for adjustable voltage output

Solar Cells

• Converts light energy to electrical energy
• Works in opposite direction of LEDs
• Used as DC power source

Resources

• Links and additional videos provided for deeper understanding
• Available at listed website and Amazon store