PHYSICS AS HELP

[halosh92]

paper 1
may.june 2004
Q 25 (plz explain with reasons)
Q 27 (how ti find ranges?)
Q 35

[astarmathsandphysics]

2mite

[astarmathsandphysics]

25)Sound waves cos the move because particles hit each other and make them move - they need matter or "stuff" to travell through. There is no matter in a vacuum C
27)B this disrupts the grains which have the magnetism
35)D use the right hand grip rule

[nid404]

Sir can u help me with Nov 06 q 30. How is the answer C...E=V/d right? so shouldn't E decrease as d increases??

[halosh92]

25)Sound waves cos the move because particles hit each other and make them move - they need matter or "stuff" to travell through. There is no matter in a vacuum C
27)B this disrupts the grains which have the magnetism
35)D use the right hand grip rule

i believe u solved the wrong paper sir 
its may june 2004 CIE

[astarmathsandphysics]

Ok. When I get home

[~Mimi~]

Nov 2006. Ques.30.
Isn't it because it's a uniform field. E is constant anywhere within the field. Is that correct?

[nid404]

but the formula E=V/d is for a uniform field......

[~Mimi~]

May / June 2004. # 35

( I hope it makes sense, lol...)

Basically R=V/I
When the resistance of the variable resistor decreases, the share of voltage across it also falls. Since the sum of the voltages across the two resistors must add up to the same old number. The share of voltage across the fixed resistor will then increase.

For the current, when resistance of the variable resistor falls. The sum of resistance in circuit ( fixed+variable) falls.
Since R= V/I. The current increases.

So the answer is D.

[~Mimi~]

but the formula E=V/d is for a uniform field......

yh, that's true.....

[~Mimi~]

googled stuff. Is this of any help whatsoever:

Uniform electric fields
What do we mean by a “uniform” field? (One that does not vary from place to place. In terms of the field lines, this means that they are parallel and evenly spaced. Also as field strength = – (potential gradient), the equipotentials should also be evenly spaced.)
Where have we seen such as field? (The field between two parallel charged plates.)
 
How will a charge move in such a field? (The force is given by
F = EQ
Since E is constant, the force will be constant and therefore, by
F = ma
the acceleration will also be constant and directed along the field lines for a positive charge and opposite to the field lines for a negative charge. (Note: A constant acceleration produces a parabolic path for the charge if it has any component of motion across the field lines, just as with projectiles in the Earth’s constant gravitational field near its surface)."

 

[nid404]

yaa but why is E constant is the question

thanks for helping tho

[~Mimi~]

May/June 2004. Question 27.
 I guess it's just estimation.
speed of light : 3 x 10^ 8 m/s
wavelength of infrared : 1000 nm to 100000 nm approx.  (let's assume, you've studied approximate wavelengths of the different radiations)
use v= f x wavelength
3 x 10^14 and 3 x 10^12.....the values u get for frequency for the wavelengths mentioned above. So, I guess it's ,safely, C.

However , I do hope someone can suggest a much simpler way, sans calculation, hopefully...

[halosh92]

May/June 2004. Question 27.
 I guess it's just estimation.
speed of light : 3 x 10^ 8 m/s
wavelength of infrared : 1000 nm to 100000 nm approx.  (let's assume, you've studied approximate wavelengths of the different radiations)
use v= f x wavelength
3 x 10^14 and 3 x 10^12.....the values u get for frequency for the wavelengths mentioned above. So, I guess it's ,safely, C.

However , I do hope someone can suggest a much simpler way, sans calculation, hopefully...

 i rili dont get the part where u substituted the velocity with 3 x 10^14
isnt it supposed to be 3 x 10^ 8 m/s
and how did u get 3 x 10^12
thxxx

[halosh92]

nov 2003
cie
physics AS


Q4
Q8 (explanation)
Q11
Q12
Q14
Q16
Q24
Q28

VERY URGENT! PLZ