physics paper 3 doubt! please help :(!

[vivi2003]

Please help me to solve the last question
http://www.xtremepapers.me/CIE/Cambridg ... _qp_31.pdf

can anyone show me how to draw this correctly? cause I'm a bit confused with the first one
Thank you so much in advance! :good:

 

[zkapoor]

Please help me to solve the last question
http://www.xtremepapers.me/CIE/Cambridg ... _qp_31.pdf

can anyone show me how to draw this correctly? cause I'm a bit confused with the first one
Thank you so much in advance! :good:

The first one is a straight horizontal line anywhere above the middle of the graph.
The second one is a regular AC wave
Third one is only the top halves of a regular AC wave, for what would be the bottom half the voltage is at 0. Kinda looks like a bunch of hills with flatland between

 

[unplugged]

 

[vivi2003]

Please help me to solve the last question
http://www.xtremepapers.me/CIE/Cambridg ... _qp_31.pdf

can anyone show me how to draw this correctly? cause I'm a bit confused with the first one
Thank you so much in advance! :good:

The first one is a straight horizontal line anywhere above the middle of the graph.
The second one is a regular AC wave
Third one is only the top halves of a regular AC wave, for what would be the bottom half the voltage is at 0. Kinda looks like a bunch of hills with flatland between

thankyou so much! :Yahoo!: :friends:

 

[igcse2011]

Need Help with :
1-use the term half-life in simple calculations, which might involve information in tables or decay curves.
2-use and describe use of a cathode-ray oscilloscope to display waveforms.
3-Explain why energy losses in cables are lower when the voltage is high ?
4-Describe an experiment to measure specific latent heats for steam and for ice and experiment for specific heat capacity

 

[zkapoor]

I can help you with the third one.
Energy loss is power loss into time, and power (hence power loss) is calculated by I^2*R. The reason V isn't used is because the voltage constantly changes from point to point on the wire (think of the wire as thousands of small resistances dividing the voltage). Hence high voltage = low current = low power loss = low energy loss
You can also mention the heating effect of current

 

[unplugged]

Need Help with :
1-use the term half-life in simple calculations, which might involve information in tables or decay curves.
2-use and describe use of a cathode-ray oscilloscope to display waveforms.
3-Explain why energy losses in cables are lower when the voltage is high ?
4-Describe an experiment to measure specific latent heats for steam and for ice and experiment for specific heat capacity

1. Half life is used to refer to the time taken for half a sample of radioactive material to decay and observation says that the rate of decay is based on the size of the sample. So every half life duration the rate of decay is halved. This leads exponential reduction in the decay rate.

2. The oscilloscope can be used to monitor voltage and frequency of an ace supply. The AC supply terminals are connected across the Y plates and this generates an alternating up and down motion for the cathode ray as the ray of electrons is bent back and forth by the alternating charge on the terminals.
A DC current is connected to the X plates in order to provide movement of the ray along the X axis and this power supply provides a time stamp indicating the frequency in which the AC current operates.

3. Because higher voltage produces lower current and this in turn results in lower energy loss in the form of heat in the wires. Because the energy lost in the
wires can be quantized as Resistance x current^2, so as the current goes lower the power loss is lower.

4. By using an electric heater , a cone filled with ice is heated and a beaker is placed below it. After collecting a certain volume of water , the volume of water can be measured and the power used by the heater can be measured based on time and we can calculate how much power was needed to melt this volume of ice.