A2 Physics | Post your doubts here

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We have to clear this solution cz its a main point in the syllabus.
(b) Candidates should be able to recall that a carrier wave, amplitude modulated by a single audio
frequency, is equivalent to the carrier wave frequency together with two sideband frequencies.
Here's what the textbook says on this matter:





Sorry for the bad quality :D
 

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AOA.. That two points mean that when reflected ultrasound is received by the probe the successive compression and rarefaction of ultrasound wave causes the crystal to vibrate. Such that the positive and negative no longer coincides and crystals vibrate, as a result a voltage is produced . which is thn amplified and fed to an c.r.o.
it is just like how a microphone works.
 
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work done= pressure x change in volume
change in volume= (2.1 x 10^3 x 10^-6)-(1.8 x 10^3 x 10^-6)
w.d= 1.o x 10^5 x change in volume..

dont forget to change cm(cube) to metre(cube)!
how do you know the pressure?? Isn't the pressure going to be atmospheric pressure + pressure exerted on the gas??
thanks :)
 
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how do you know the pressure?? Isn't the pressure going to be atmospheric pressure + pressure exerted on the gas??
thanks :)
well in derving work done = p delta v....we assumed the gas expanding or contracting against constant external pressure....chek chapter 4 chriss mee book for frther clarification
 
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Its said that plate P is earthed which means its at zero volts. And The Gravitational Force is acting downwards on the Oil droplet, the opposite force therefore is upwards since its stationary. Since Plate P is at zero, Plate Q has to be positive and since there is an attractive force acting upwards to keep the oil droplet stationary, it has to be negative.
 
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Its said that plate P is earthed which means its at zero volts. And The Gravitational Force is acting downwards on the Oil droplet, the opposite force therefore is upwards since its stationary. Since Plate P is at zero, Plate Q has to be positive and since there is an attractive force acting upwards to keep the oil droplet stationary, it has to be negative.
thanks..could you help me with Q3 b ii part 1..how to find amplitude? http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w08_qp_4.pdf
 
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