Chapter III of Computer Network will teach you about Physical Layer and it is of 4 teaching hrs.
This chapter will provide you information about 3.1. Guided Media: Copper, Fiber cabling and its capacity standards 3.2. Unguided Media: Bluetooth, Wi-Fi/Wireless-LAN, Satellite Communication Basics (Micro waves, Radio waves) 3.3. Circuit/packet/message switching 3.4. ISDN Signaling & Architecture 3.5. Network Performance: Bandwidth, Throughput, Latency, Bandwidth-Delay Product, Jitter