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Define modulation index.
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In a series LCR circuit connected to an a.c. source of voltage v = vmsinωt, use phasor diagram to derive an expression for the current in the circuit. Hence, obtain the expression for the power dissipated in the circuit. Show that power dissipated at resonance is maximum
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In a series LCR circuit, VL = VC ≠ VR. What is the value of power factor?
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State three important factors showing the need for translating a low frequency signal into a high frequency wave before transmission
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Draw a sketch of a sinusoidal carrier wave along with a modulating signal and show how these are superimposed to obtain the resultant amplitude modulated wave
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How are infrared waves produced?
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What role dose infra-red radiation play in maintain the Earth’s warmth
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What role dose infra-red radiation play in physical therapy?
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A series LCR circuit is connected across an a.c. source of variable angular frequency 'ω'. Plot a graph showing variation of current 'i' as a function of 'ω' for two resistances R1 and R2 (R1 > R2).
Answer the following questions using this graph :
(a) In which case is the resonance sharper and why?
(b) In which case in the power dissipation more and why?
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State Lenz's law. Illustrate, by giving an example, how this law helps in predicting the direction of the current in a loop in the presence of a changing magnetic flux.
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Define the term 'intensity of radiation' in terms of photon picture of light.
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How are side bands produced?
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Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.
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Identify the part of the electromagnetic spectrum which is:
produced by bombarding a metal target by high speed electrons.
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Name the parts of the electromagnetic spectrum which is
used to treat muscular strain.
Write in brief, how these waves can be produced.
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Name the parts of the electromagnetic spectrum which is
used as a diagnostic tool in medicine.
Write in brief, how these waves can be produced.
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The carrier wave is given by
C(t) = 2sin(8πt) volt.
The modulating signal is a square wave as shown. Find modulation index.
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If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
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Describe a simple experiment (or activity) to show that the polarity of emf induced in a coil is always such that it tends to produce a current which opposes the change of magnetic flux that produces it.
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To which part of electromagnetic spectrum does a wave of frequency 3 × 1013 Hz belong?
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