Biology; Chemistry; Physics: Post your doubts here!

[TheStallion-Reborn]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w12_qp_22.pdf QUESTION 10 PART B. help!!!

 

[Hskk]

no. the voltmeter also increases. because the voltage across thermistor decreases, (because the resistance decreases) so decrease in the pd across thermistor means increase in the voltage across the fixed resistor(the one across which is the voltmeter)

Oh yeah!! Thanks.

 

[Saad Mughal]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w12_qp_22.pdf QUESTION 10 PART B. help!!!

This is your basic ray box experiment for light.
Equipment: Light source/Ray box, plane mirror, a handful of pins, protractor, wooden barrier.
The light source (or ray box) is placed at an angle to the plane mirror and is turned on. Two or three pins are placed to show the light rays incident from the light source (incident ray), two more pins are used to show the reflected rays from the mirror. A wooden barrier is placed at the normal to the plane mirror (where the light rays strike the mirror) and the angle of incidence and angle of reflection are measured using the protractor. The experiment is repeated at different angles of incidence (by moving the light source) and it is seen that the angle of incidence is always equal to the angle of reflection. Thus, proving the law(s) of reflection.
Hope that helps

 

[TheStallion-Reborn]

This is your basic ray box experiment for light.
Equipment: Light source/Ray box, plane mirror, a handful of pins, protractor, wooden barrier.
The light source (or ray box) is placed at an angle to the plane mirror and is turned on. Two or three pins are placed to show the light rays incident from the light source (incident ray), two more pins are used to show the reflected rays from the mirror. A wooden barrier is placed at the normal to the plane mirror (where the light rays strike the mirror) and the angle of incidence and angle of reflection are measured using the protractor. The experiment is repeated at different angles of incidence (by moving the light source) and it is seen that the angle of incidence is always equal to the angle of reflection. Thus, proving the law(s) of reflection.
Hope that helps

thnku! i gues v have another marking scheme error.http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w11_qp_21.pdf question 6 part a sub part 2, http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w11_ms_21.pdf

 

[Saad Mughal]

thnku! i gues v have another marking scheme error.http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w11_qp_21.pdf question 6 part a sub part 2, http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w11_ms_21.pdf

No. It's correct. When the number of turns increases, the frequency of the output voltage becomes higher and so does the highest value of voltage (amplitude).

 

[Kamihus]

Is it just me or are the 1 invariants of all the papers i.e paper 11, 21,41 more difficult than, 12, 22, 42?

MCQs are almost the same, the other two do look a bit difficult

 

[asma tareen]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w12_qp_22.pdf
Q9 part d ii
how will we make the graph??

 

[usama321]

Why does sulfur get deposited on the anode when dilute copper sulphate is electrolysed with carbon electrodes
Plz help Saad Mughal

actually supher is not deposited to the anode. At cathode, the Cu ions turn to Copper, this is so because copper is less reactive than Hydrogen so it should travel to the cathode.

At anode, the OH- would travel there in prefrence of SO4-, and form water, oxygen and give off electrons.

At cathode : Cu 2+ + 2e- == Cu

At anode : OH- == 2H2O + O2 + 4e-

 

[papajohn]

actually supher is not deposited to the anode. At cathode, the Cu ions turn to Copper, this is so because copper is less reactive than Hydrogen so it should travel to the cathode.

At anode, the OH- would travel there in prefrence of SO4-, and form water, oxygen and give off electrons.

At cathode : Cu 2+ + 2e- == Cu

At anode : OH- == 2H2O + O2 + 4e-

From the equation, copper is deposited as it ions are discharged at cathode. In this case, Copper(II) sulphate concentration would be lower. Now we left with So4 ions.

 

[usama321]

From the equation, copper is deposited as it ions are discharged at cathode. In this case, Copper(II) sulphate concentration would be lower. Now we left with So4 ions.

you have to consider that it is a solution, dilute means it has water. So we have these 4 ions, H+, OH- (from water) and Cu2+, SO4-2. From these, Cu is more stable than H, so it would be deposited at the cathode. We know that SO4 is never deposited in aqueous solution, so it would be OH- at the anode

 

[usama321]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w12_qp_22.pdf
Q9 part d ii
how will we make the graph??

It should be like this. At first the rate of change of distance increases for some seconds, and then it becomes constant

 

[usama321]

It should be like this. At first the rate of change of distance increases for some seconds, and then it becomes constant
View attachment 24306

the diagram is not exact, but you get the general idea

 

[papajohn]

the diagram is not exact, but you get the general idea

When acceleation the distance will be more than the at constant speed.. But why more distance at contant???

 

[usama321]

When acceleation the distance will be more than the at constant speed.. But why more distance at contant???

Read the whole question, it says that it first accelerates and then becomes constant. Furthermore, the graph represents the total distance from the start of the motion. At first, the distance covered by the body each second slowly increases (aceleration) and then it becomes constant (steady slope)

 

[asma tareen]

It should be like this. At first the rate of change of distance increases for some seconds, and then it becomes constant
View attachment 24306

thnx dude

 

[Saad Mughal]

Why does sulfur get deposited on the anode when dilute copper sulphate is electrolysed with carbon electrodes
Plz help Saad Mughal

Sulphur is never deposited, at the anode (in all solutions of sulphates) oxygen gas is given off, this is because sulphate ions are more stable and tend to stay in ionic form and do not give away their electrons easily. Hydroxide is more easily discharged and hence oxygen gas forms. At the anode, copper ions gain electrons and copper is deposited. usama321 has summed up the equations for the reaction. Hope that helps.

 

[fatima0000]

a) explain how a physical property which varies with temperature may be used for the measurement of
temperature and state examples of such properties.
explaination???

 

[Saad Mughal]

a) explain how a physical property which varies with temperature may be used for the measurement of
temperature and state examples of such properties.
explaination???

A physical property such as:
Volume of fixed mass of liquid is used in liquid in glass thermometers.
Voltage produced by two conducting wires is used in thermocouples.
Pressure of a fixed mass of gas at constant volume is used in gas thermometers.
Resistance of a variable resistor (such as thermistor).
The most common (in labs and clinics) is the liquid in glass thermometer.
Hope that helps.

 

[fatima0000]

what are the experiments to show total internal reflection???

 

[TheStallion-Reborn]

what are the experiments to show total internal reflection???

tag me whn u get the answr