Suggest an editImprove this articleRefine the answer for “What units of measurement are used at the physical layer?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**At the physical layer**, the units of measurement relate to the signal and the transmission speed, not to data (packets, frames, and so on). **Key point:** the main units are bps (transmission speed), hertz (frequency), volts (voltage), decibels (attenuation), and meters (line length).Shown above the full answer for quick recall.Answer (EN)ImageAt the **physical layer**, the **units of measurement relate to the signal and the transmission speed**, not to data (packets, frames, and so on). Put simply: here you measure **how fast, and in what form, the signal is transmitted**. --- ## Main units of measurement at the physical layer ### 1. **Bits per second (bps)** This is the **main unit** of the physical layer. It shows: > how many bits (0 and 1) are transmitted in one second Examples: - 10 Mbps - 100 Mbps - 1 Gbps - 10 Gbps Important: **bps is not bytes**, 1 byte = 8 bits. --- ### 2. **Hertz (Hz)** Used to describe: - signal frequency - channel bandwidth Examples: - 100 MHz - 2.4 GHz (Wi-Fi) - 5 GHz (Wi-Fi) Put simply: > Hertz shows **how fast the signal oscillates**. --- ### 3. **Volt (V)** Used in wired networks. It shows: - the electrical voltage level - the difference between logical 0 and 1 Example: - 0 V is logical 0 - 5 V is logical 1 (the exact values depend on the standard) --- ### 4. **Decibel (dB)** Used to assess: - signal attenuation - interference level - line quality Put simply: > dB shows **how much the signal has weakened or been amplified** --- ### 5. **Meters (m)** Yes, this is a physical layer unit too. Used for: - the maximum cable length Examples: - twisted pair Ethernet: up to 100 m - fiber optic: kilometers --- ## What is not measured here The physical layer **does NOT use**: - frames - packets - IP addresses - MAC addresses - number of users That is all handled by higher layers. --- ## Short answer for the interview > **The physical layer uses units of measurement related to the signal**: > bps (transmission speed), hertz (frequency), volts (voltage), decibels (attenuation), and meters (line length).For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.