Define frequency and its unit.

Short Answer:

Frequency is the number of cycles or repetitions of a wave that occur in one second. In electrical terms, it refers to how many times an alternating current (AC) changes direction per second. It is an important characteristic of AC signals and waveforms.

The unit of frequency is Hertz (Hz). One Hertz means one complete cycle per second. For example, if a signal completes 50 cycles in one second, its frequency is 50 Hz. In India, the standard power supply frequency is 50 Hz.

Detailed Explanation:

Frequency and Its Unit

Frequency is a key concept in electrical engineering that defines how often a repeating event occurs in a given amount of time. In the context of electricity, frequency tells us how many times the current or voltage alternates its direction in one second.

When dealing with alternating current (AC), voltage and current continuously change from positive to negative and back again. Each full swing from zero to positive, then to negative, and back to zero is called one cycle. The number of these cycles in one second is the frequency.

Mathematically,
Frequency (f) = 1 ÷ Time Period (T)
Where:

  • f is the frequency in Hertz (Hz)
  • T is the time taken to complete one cycle (in seconds)

If one cycle takes 0.02 seconds, the frequency will be:
f = 1 ÷ 0.02 = 50 Hz

Importance of Frequency

  1. Standardization:
    • Electrical power systems around the world follow a standard frequency.
    • In most countries like India, the frequency is 50 Hz. In the USA, it’s 60 Hz.
  2. System Compatibility:
    • Electrical devices are designed to operate at a specific frequency.
    • Using the wrong frequency can damage equipment or affect performance.
  3. Waveform Behavior:
    • Higher frequency means faster changes in current direction.
    • This affects the design of transformers, motors, and filters.
  4. Signal Processing:
    • In communication and electronics, frequency helps in filtering, tuning, and modulation.
    • Different frequency ranges are used for different applications like radio, TV, and internet.

Unit of Frequency

The unit of frequency is Hertz (Hz), named after the German physicist Heinrich Hertz, who first proved the existence of electromagnetic waves.

  • 1 Hz = 1 cycle per second
  • 1 kHz (kilohertz) = 1,000 Hz
  • 1 MHz (megahertz) = 1,000,000 Hz
  • 1 GHz (gigahertz) = 1,000,000,000 Hz

These larger units are used in electronics and communication systems to represent signals with higher frequency.

Real-Life Examples:

  • Electricity Supply: 50 Hz AC in homes
  • Radio Waves: 100 MHz FM radio
  • Wi-Fi: Operates at 2.4 GHz or 5 GHz
  • Mobile Phones: Use signals in MHz to GHz range

Understanding frequency is crucial for designing electrical systems, tuning circuits, and ensuring the proper functioning of electrical and electronic devices.

Conclusion:

Frequency is defined as the number of complete cycles or waves that occur in one second. It is a basic and important property of alternating signals and is measured in Hertz (Hz). Frequency plays a major role in electrical systems, signal processing, and communication technologies. Accurate knowledge of frequency ensures proper operation of devices and power systems.