Physic-Homework

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week15R: EM in our life more / Radio and TV

1. How Radio Waves Are Produced / antennas
	https://www.youtube.com/watch?v=eNouTh7S_ys

2. AM and FM radio
	https://www.youtube.com/watch?v=-qyx8XV8dtE

3. how choose radio station / LC circuit / 
	https://www.youtube.com/watch?v=vhopbp-vMD4
 

 4. CRT-TV
 	https://www.youtube.com/watch?v=K-kxIP3FhCk
 	https://www.youtube.com/watch?v=rwxARHm1Qwk
	
 5. LCD TV
 	https://www.youtube.com/watch?v=0B79dGR19Tg
	https://www.youtube.com/watch?v=82KaxKyuwV4
	https://www.youtube.com/watch?v=k7xGQKpQAWw
		
 6. Plasma TV
 	https://www.youtube.com/watch?v=nNxg90S8Vo8
	
7. LED TV and OLED TV
	https://www.youtube.com/watch?v=8quZrUcRFlw
8 Others: 	industrial generators
	wind energy
	https://www.youtube.com/watch?v=DILJJwsFl3w

	hydro energy
	https://www.youtube.com/watch?v=Lx6UfiEU3Q0
	https://www.youtube.com/watch?v=rnPEtwQtmGQ
	
	nuclear energy
	https://www.youtube.com/watch?v=VrhzkoNU84g
	https://www.youtube.com/watch?v=_UwexvaCMWA
	
	Geothermal Energy
	https://www.youtube.com/watch?v=mCRDf7QxjDk
	
	solar energy
	https://www.youtube.com/watch?v=wfDWDqyToBg
	
	fossil fuel, wood, and coal traditional thermal power
	https://www.youtube.com/watch?v=IdPTuwKEfmA

9. Others: batteries
	https://www.youtube.com/watch?v=9OVtk6G2TnQ
	
	lead acid battery
	https://www.youtube.com/watch?v=HhxtfULIO7c
	
	dry battery (Zn-based)
	https://www.youtube.com/watch?v=UEPJXSXw7HA
	
	rechargable (Ni-Cd)
	?
	
	lithium ion
	?
	
	solar panel
	?
	
	fuel cell
	?
	
	

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Explanation & Answer

there you go buddy
there you go buddy

Running head: PHYSICS

1

Student name
Student affiliation

PHYSICS

2

1. How an antenna works
An antenna transmits or receives electromagnetic waves in form of waves and
troughs, which have different wavelengths of which are also dependent on the
transmitting antennae. Radiated energy is emitted outward from the antenna that produces
it. Half a wavelength is considered a dipole. The electron flow is characterized by
fluctuations in the magnetic fields. It is maximum in a certain direction of flow and
maximum when the direction changes. E and H fields are perpendicular to each other and
represent the time phase and space curvature of the waves. They are reversed in every
half wave while maintaining the direction of progress of the waves – the pointing vector
rule. This rule is reversed when the waves hit a reflective surface. In such a scenario, the
H field remains unchanged while the E field will be reversed, as well as the direction of
propagation of the wave.

2. Wave modulation
Modulation is the process of varying the properties of a high frequency periodic wave
form i.e. the carrier signal to transmit information. It mixes low frequency information
with high frequency information by concealing the low frequency message in a high
frequency wave. Amplitude modulation and frequency modulation are the most popular
modulation techniques.

Modulatory signal
Modulator
Sine signal

carrier

Modulator
carrier

Demodulation

Information

PHYSICS

3

Amplitude modulation is dependent on the amplitude and has a narrower frequency band.

High frequency sine wave
Frequency of carrier signal

Amplitude of message signal

Frequency modulation uses the amplitude of the message signal to vary the
frequency of the carrier sine wave. It occupies a wider frequency band.

3. Radio frequency and L.C circuits
Radio waves are transmitted, propagated and received by antennas and converted to
alternating current by and inductor which detect electromagnetic waves. This creates a
magnetic field which in turn is conveyed to a second circuit and produces an alternating
current too. In the second circuit/coil, desired frequencies are transmitted through the
detector diode and sound is heard, while for undesired frequencies, the current is passed
to the ground. L.C. circuits consist of and inductor, a capacitor and an alternating current

PHYSICS

4

voltage. The frequency is inversely proportional to (2π) multiplied by the square root
of(inductance × capacitance)

4. Cathode ray t...


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