DISCUSS PHYSICSSSS!!

[Dashey]

hey guys
CHEMISTRY DOWN
PHYSICS TO GO!!
duznt matter how ur chem went jus chuck it..
and concentrate on physics and promise urself
to do better in it.!!!
so lets discuss physics!!
i fink its an easy subject and we can easily achieve 'A' in it..
if our concepts are clear!!
but i really hate that electricity chapter man!!
so lets discuss the topics we're weak in ova here.!!
and together we're gonna ace it!!

 

[saad]

elec is hard but man is heat lengthy or what
takes ages to get the solution
and even then it is mostly incorrect

 

[Dashey]

yeah man u right..thermal is the most irritating topic ya'knw..
for dat topic i'll suggest u to learn the thermometer's properties (RANGE,SENSITIVITY AND LINEARITY)..
all ov it!!
dey are really important*
P.S
memorize the definitions of specific and latent heat capicity..
FORMULAS :-
thermal energy = mass x specific heat capacity x change in temperature.
(calculate heat transferred in a change of state using the formula) thermal energy = mass*specific latent heat.
thats all..!!

 

[Zishi]

Hello, people! I'm also kinda weak in the electro-magnetism and these A.C generators and D.C motors. Plus, I really want to get in A* in it!

 

[Dashey]

ayy zishi...raynotes dun even hav the perfect notes for that chapter!!
bt checkout dis website!!
dey have the greatest electricty notes i've seen anywhere!!

 

[sahar]

which website u toking about ???! n are dere sume where notes of half lyfe n awl dat ?? i neva get it dat part ov physics !

 

[Dashey]

yeah they have it under the name of 'ALPHA BETA GAMMA RAYS'!
http://www.astarmathsandphysics.com/o_l ... _menu.html

 

[Chief Examiner]

i advise u to concentrate on federal book and this is enough for distinction.

 

[Dashey]

man dat book is sooo complexed!!!! :S
p.s do check out dez short but really cool notes aswell..!!

 

[sunshine]

my prep is toooooooooooooooooooooooo gud.!
i have done everything.!
past papers from 1990 to 2009 WAO :O:O

 

[farrukh]

my prep is toooooooooooooooooooooooo gud.!
i have done everything.!
past papers from 1990 to 2009 WAO :O:O

thats great yar
if you have time can you help me on these topics?
viewtopic.php?f=25&t=1176

 

[sahar]

m m which federal book u ppl toking about ??? charles chew ?? n anyone referring avison ?!

 

[Dashey]

*¬*¬*¬*¬*FOR FARRUKH*¬*¬*¬*¬

1. Simple Experiments to show the Reflection of Sound..
Ans.When sound reflects off a special curved surface, it will bounce out in a straight line irrespective of wherever it originally hits. The sound will go directly into the audience. It will travel from one focus to the other, no matter where it strikes the wall. Say for example, if your friend stands at one focus and you stand at the other, his or her whisper will be heard clearly by you. And no one in the rest of the room will be able to hear anything. Reflection is responsible for many interesting phenomena. When sound waves bounce off obstacles and reflect the sound many times, it generates a process called multiple reflection of sound. This reflection happens before reaching the destination or the target. The best example of this multiple sound reflection is a stethoscope in which sound waves reflect through the tube many times before reaching the ears of the doctor who is examining the heart beats or lungs.
Multiple reflection of sound has many uses. One of the common uses can be seen in megaphones or loudhailers and horns of the vehicles. Another example where multiple reflection of sound is commonly used is the musical instrument, such as trumpets and shehanais. These instruments of course are designed to send sound in a particular direction. Sound is not sent in all direction. In trumpets and shehanais, for example a tube followed by a large conical opening reflects sound successively to guide most of the sound waves from the source (mouth of the instrumentalist) in the forward direction towards audience. Similarly, stethoscope is a medical instrument used for listening to sounds produced within the body. The doctor can hear the sound of the patient’s heartbeat through the process called multiple reflection of sound. The stethoscope therefore is the best example of multiple reflection of sound.

2. Describe the factors which influence the quality (timbre) of sound waves
Ans. All objects have a natural frequency or set of frequencies at which they vibrate. The quality or timbre of the sound produced by a vibrating object is dependent upon the natural frequencies of the sound waves produced by the objects. Some objects tend to vibrate at a single frequency and they are often said to produce a pure tone. A flute tends to vibrate at a single frequency, producing a very pure tone.

3. Use of ultra sound in quality control
Ans. Ultrasound is any sound of frequency greater than 20 000 Hz(more than a normal human hearing range). Ultrasound waves are partially reflected when they meet a boundary between two different media. The time taken for the reflections to reach a detector is a measure of how far away such a boundary is.
Ultrasound waves can be used in industry for cleaning and quality control.

4. The environmental and cost implications of underground power transmission compared to overhead lines.
Ans. Electricity is transmitted at high voltages (110 kV or above) to reduce the energy lost in long distance transmission. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher cost and greater operational limitations but is sometimes used in urban areas or sensitive locations.

5. State the meaning of the terms processor, output device and feedback.
Ans. Output devices in electronic systems transfer energy from the electrical energy that has been processed to another kind of energy, often light, sound or movement (kinetic).
Output devices can be digital or analogue. A Feedback system, in general engineering terms, is a system whose output if fed back to the input, and depending on the output, your input is adjusted so as to reach a steady-state. In colloquial language, you adjust your input based on the output of your system so as to achieve a certain end, like minimizing disturbance, cancelling echo (in a speech system) and so on.

i'm sorry i've not prepared the CRO chapter as it is on choice..anyways hope dez help you!

 

[shahoo]

bullshit

 

[Dashey]

bullshit

what happened man?

 

[sunshine]

@ Dashey : hahahahahhahahahahahaha.!

 

[Zishi]

i'm sorry i've not prepared the CRO chapter as it is on choice..anyways hope dez help you!

Dude, c'mon? CRO is the examiner's favorite topic and in NO way it is optional. Only electronic systems is optional. =/

 

[Dashey]

ohh my mistake man...i accidentally wrote CRO instead of ELECTRONICS..
hehe
the last question is answered is also related to the CRO chapter!!

 

[farrukh]

*¬*¬*¬*¬*FOR FARRUKH*¬*¬*¬*¬

1. Simple Experiments to show the Reflection of Sound..
Ans.When sound reflects off a special curved surface, it will bounce out in a straight line irrespective of wherever it originally hits. The sound will go directly into the audience. It will travel from one focus to the other, no matter where it strikes the wall. Say for example, if your friend stands at one focus and you stand at the other, his or her whisper will be heard clearly by you. And no one in the rest of the room will be able to hear anything. Reflection is responsible for many interesting phenomena. When sound waves bounce off obstacles and reflect the sound many times, it generates a process called multiple reflection of sound. This reflection happens before reaching the destination or the target. The best example of this multiple sound reflection is a stethoscope in which sound waves reflect through the tube many times before reaching the ears of the doctor who is examining the heart beats or lungs.
Multiple reflection of sound has many uses. One of the common uses can be seen in megaphones or loudhailers and horns of the vehicles. Another example where multiple reflection of sound is commonly used is the musical instrument, such as trumpets and shehanais. These instruments of course are designed to send sound in a particular direction. Sound is not sent in all direction. In trumpets and shehanais, for example a tube followed by a large conical opening reflects sound successively to guide most of the sound waves from the source (mouth of the instrumentalist) in the forward direction towards audience. Similarly, stethoscope is a medical instrument used for listening to sounds produced within the body. The doctor can hear the sound of the patient’s heartbeat through the process called multiple reflection of sound. The stethoscope therefore is the best example of multiple reflection of sound.

2. Describe the factors which influence the quality (timbre) of sound waves
Ans. All objects have a natural frequency or set of frequencies at which they vibrate. The quality or timbre of the sound produced by a vibrating object is dependent upon the natural frequencies of the sound waves produced by the objects. Some objects tend to vibrate at a single frequency and they are often said to produce a pure tone. A flute tends to vibrate at a single frequency, producing a very pure tone.

3. Use of ultra sound in quality control
Ans. Ultrasound is any sound of frequency greater than 20 000 Hz(more than a normal human hearing range). Ultrasound waves are partially reflected when they meet a boundary between two different media. The time taken for the reflections to reach a detector is a measure of how far away such a boundary is.
Ultrasound waves can be used in industry for cleaning and quality control.

4. The environmental and cost implications of underground power transmission compared to overhead lines.
Ans. Electricity is transmitted at high voltages (110 kV or above) to reduce the energy lost in long distance transmission. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher cost and greater operational limitations but is sometimes used in urban areas or sensitive locations.

5. State the meaning of the terms processor, output device and feedback.
Ans. Output devices in electronic systems transfer energy from the electrical energy that has been processed to another kind of energy, often light, sound or movement (kinetic).
Output devices can be digital or analogue. A Feedback system, in general engineering terms, is a system whose output if fed back to the input, and depending on the output, your input is adjusted so as to reach a steady-state. In colloquial language, you adjust your input based on the output of your system so as to achieve a certain end, like minimizing disturbance, cancelling echo (in a speech system) and so on.

i'm sorry i've not prepared the CRO chapter as it is on choice..anyways hope dez help you!

Thankyou so much yar I really appreciate your effort and it helped alot but the first problem remains unclear..
I asked about refraction of sound waves and not reflection it seems you have misread it..Anyways thanks for your help

 

[Aizen]

hey guys ive done da pprs just from 2004 to 2009.but wenever i see a question i can easily solve it.is it enuf for tomorrow's physics ppr?