Physical Layer of the OSI Model: Definition, Components & Media

Lesson Transcript
Instructor: Meghalee Goswami

Meghalee has a masters of computer science and communication engineering.

This lesson discusses the physical layer of the OSI model. It also discusses the various components and media used in this layer for the transfer of data. Wired data transmission in the physical layer and its associated components will be broadly covered. Updated: 03/08/2021

The OSI Model Physical Layer

OSI stands for Open Systems Interconnection Model. The physical layer in the OSI Model is the lowest layer and is used for transmitting data in its basic form: bit-level. The transmission medium can either be wired or wireless. Physical layer components in a wired model include cables and connectors that are implemented for carrying data from one place to another. Data is transmitted in the form of electromagnetic signals, which translates to a stream of bits. Over the past few years, there has been rapid growth in wireless data transmission as well. Due to the availability of internet, Wi-Fi and Bluetooth communications are becoming a norm.

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  • 0:04 The OSI Model Physical Layer
  • 0:42 Physical Layer Components
  • 1:18 Physical Layer Cable Types
  • 1:53 Physical Layer Cable…
  • 2:30 Physical Layer…
  • 2:48 Lesson Summary
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Physical Layer Components

Basic hardware components used in the OSI physical layer include network interface cards (NICs), connectors and interfaces, and cables that facilitate the transmission of data from source to destination.

Network Interface Card
Network card

The Network Interface Card is a component installed in a computer in order to connect it to any available network. Connectors and Interfaces are used to connect cables from one source to another. Depending upon the type of cable used, connectors are chosen accordingly. Cables are physical components that carry electromagnetic or optic signals through them and transmit them from a network source to a network destination.

Physical Layer Cable Types

There are 3 main types of cables used in networking: shielded twisted pair, unshielded twisted pair, and coaxial.

  • Shielded Twisted Pair: This cable type involves placing foil shielding around pairs of twisted wires to prevent electromagnetic interference.

Shielded Twisted Pair Cable
Shielded twisted pair

  • Unshielded Twisted Pair: This cable type is made the same way as a shielded twisted pair but without the extra foil shielding around the wires.

Unshielded Twisted Pair Cable
Unshielded twisted pair

  • Coaxial cable: This cable type contains a wire covered by alternative conducting and insulating shields. This makes the cable more reliable when connecting different networks.

Coaxial Cable
Coaxial Cable

Physical Layer Cable Connections

Just like we have different cables used for creating networks, we also require specific types of connectors that connect these cables based on network type:

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An NIC is used for which of the following?

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