A2 Physics | Post your doubts here

[Goku]

Can someone please explain me A-scan and B-scan in ultrasound? :/

 

[angelgirl:)]

ppl give me a simple defination of smoothing...?

 

[namename]

Mark scheme contradicting.
Check this out

answer to june 2002 6biii) in which how a capacitor can be used in smoothing is by connecting a capacitor across SQ.
but answer to another same question in another year(which i don't exactly remember when) says connect capacitor parallel to the load (resistor)
but both ms does not give the alternative answers (to each other)
what is correct?

 

[angelgirl:)]

ppl give me a simple defination of smoothing...?

and how the amount of smoothing is increased?

 

[namename]

ppl give me a simple defination of smoothing...?

Reduction in variation in rectified voltages

 

[SkyPilotage]

Can someone please explain me A-scan and B-scan in ultrasound? :/

The B-scan technique basically combines a series of A-scans, taken from a range of different angles, to
form a two-dimensional picture. As before, each A-scan corresponds to a single ultrasound pulse being
emitted by the transducer and producing a series of reflected pulses from boundaries within the body.

ppl give me a simple defination of smoothing...?

the process by which there is less variations in the output by creating small ripples across the peaks of the waves.

 

[SkyPilotage]

Mark scheme contradicting.
Check this outView attachment 9367

answer to june 2002 6biii) in which how a capacitor can be used in smoothing is by connecting a capacitor across SQ.
but answer to another same question in another year(which i don't exactly remember when) says connect capacitor parallel to the load (resistor)
but both ms does not give the alternative answers (to each other)
what is correct?

Simple, no contradiction. Both cases, the capacitor is parallel to the load.

and how the amount of smoothing is increased?

Increasing capacitance of capacitor parallel to resistor
Increasing resistance of resistor!

 

[Goku]

The B-scan technique basically combines a series of A-scans, taken from a range of different angles, to
form a two-dimensional picture. As before, each A-scan corresponds to a single ultrasound pulse being
emitted by the transducer and producing a series of reflected pulses from boundaries within the body.

the process by which there is less variations in the output by creating small ripples across the peaks of the waves.

Thanks!
So basically, A-scan involves single pulses being sent and received from particular points in a body,and B-scan combines all these single pulses into a 2D image?

 

[angelgirl:)]

Simple, no contradiction. Both cases, the capacitor is parallel to the load.

Increasing capacitance of capacitor parallel to resistor
Increasing resistance of resistor!

noooo...dont write increase the Resistance,...u wont get mark...chect o/n 2009 ms ppr41 Q7ci...

 

[SkyPilotage]

Nov 06 Q 1 b) Resistance thermometre has large thermal capacity, why is it small in the ms?
1 c) didnt understand the answer in the ms.

 

[namename]

Explain.. Given

Question

 

[SkyPilotage]

noooo...dont write increase the Resistance,...u wont get mark...chect o/n 2009 ms ppr41 Q7ci...

because they do not want you to alter the circuit.
Increasing resistance does increase smoothing!

 

[SkyPilotage]

Explain..View attachment 9370 Given

QuestionView attachment 9371View attachment 9372

which year?

 

[angelgirl:)]

because they do not want you to alter the circuit.
Increasing resistance does increase smoothing!

hmmm ok...

 

[user]

ppl give me a simple defination of smoothing...?

Smoothing is reduction in the variation of the power output ....

 

[user]

..

assalamoalaikum wr wb!

the graph above was correct

see we know it's gonna be negative gradient...right?

the dotted line represents the gradient..
when we take negative of it..it's gonna be reflection abt the time axis..
so this one's supposed to be correct..

i got confused with the gradient part..but it's gonna be like below...cuz for a sin curve the gradient is a cosine curve...hence it gonna be this way :

 

[SkyPilotage]

assalamoalaikum wr wb!

the graph above was correct

see we know it's gonna be negative gradient...right?

the dotted line represents the gradient..
when we take negative of it..it's gonna be reflection abt the time axis..
so this one's supposed to be correct..

i got confused with the gradient part..but it's gonna be like below...cuz for a sin curve the gradient is a cosine curve...hence it gonna be this way :
View attachment 9383

*PHEW*
Yes that makes more sense. The user "StoneBridge" really seemed to argue alot that this is wrong. I wonder about his point of view.

 

[optimistic]

please help me solve this! http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s10_qp_42.pdf
Q9 B 2.... how come resistor "R" is the input resistor? the circuit is not showing anything like that.

 

[user]

*PHEW*
Yes that makes more sense. The user "StoneBridge" really seemed to argue alot that this is wrong. I wonder about his point of view.

haha yeah....it got me confused too..then i took a moment to do it again myself..and worked this way..and finally got the answer which makes sense Alhumdulilah..
happy..abt it..
this was a question which i left cuz i didnt know and nowi did it

P.S. To avoid unnecessary confusions among members, i removed that post of mines

 

[SkyPilotage]

please help me solve this! http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_42.pdf
Q9 B 2.... how come resistor "R" is the input resistor? the circuit is not showing anything like that.

I think you need to review non-inverting amplifiers.