# AP Inter 2nd Year Physics Notes Chapter 16 Communication Systems

Students can go through AP Inter 2nd Year Physics Notes 16th Lesson Communication Systems will help students in revising the entire concepts quickly.

## AP Inter 2nd Year Physics Notes 16th Lesson Communication Systems

→ Communication is the process of sending and receiving the information by some device.

→ Attenuation is the decrease in signal strength due to energy losses as it travels.

→ Transducers converts energy from one form to another.

→ Band width is the frequency range of a modulated signal,

→ Transmitter is the part of communication system, which sends out the information.

→ The infrared radiation trapped by the atmosphere so as to keep the earth’s surface warm is called green house effect.

→ Modulation is the process of combining low frequency audio signal with high frequency carrier wave.

→ Demodulation is the process of recovering the information from the modulated wave.

→ Ionosphere is the gaseous envelope surrounding the earth.

→ Radio waves travelling directly from transmitting station to the receiving station over the earth surface are called ground wave.

→ The waves which reach the receiving station from transmission station after reflection from ionosphere are called sky waves.

→ Remote sensing is a method to get information about the size, colour, nature and location of an object from a distance.

Formulae

→ Length of Hertz antenna l = $$\frac{\lambda}{2}=\frac{\mathrm{C}}{2 v}$$

→ Length of marconi antenna l = $$\frac{\lambda}{4}=\frac{C}{4 v}$$

→ dT = $$\sqrt{2 \mathrm{Rh}_{\mathrm{T}}}=\sqrt{2 \mathrm{Rh}_{\mathrm{R}}}$$

→ Modulation index in Amplitude modulation (ma) = $$\frac{\mathrm{E}_{\max }-\mathrm{E}_{\min }}{\mathrm{E}_{\max }+\mathrm{E}_{\min }}$$

→ Band width nA.M = 2 × Frequency of modulated signal.

→ Modulation index in frequency modulation mf = $$\frac{f_{\max }-f_c}{f_m}=\frac{f_c-f_{\min }}{f_m}$$

→ Band width of F.M = 2n × Frequency of modulated signal.