O lvl physics quests

amusing_dick SG

the answer provided is 76.8ohms
couldn't tally no matter how i do.. anyone has the solutions?

a student is given a lamp labelled 12v,60w.with a aid of a circuit diagram,descirbe an experiment to enable the student to plot the voltage/current (V/I) characteristics graph for the lamp.

sketch a graph of the result you would expect to be obtained.(Do not use a graph paper).Explain the shape of the graph.

describe an experiment to determine values of voltage across a metallic conductor and the corresponding values of current in the conductor.Draw a labelled diagram of the circuit and explain how you would take the readings.

sketch the V?I characteristics graph for the metallic conductor and explain the shape of your graph.
kindly help? i bought the shinglee version of TYS that has no answers provided for structured questions..perhaps some1 with SAP version could share the ideal model answer with me... or maybe the highly educated ones out there could help in this..thx.

Darkness_hacker99 SG

Though I am not a physics student, but this is my first attempt to do a physics question. Smile

For question 1, first you must find the resistivity.

Then use the resistivity to do part (b)

Must wait for physics students to see if my working are correct anot. Smile

amusing_dick SG

wow is that required for combined physics?

Darkness_hacker99 SG

Yes. It's in the syllabus. Smile

jay_rocks SG

x2. Very Happy

amusing_dick SG

hey how about the other “essay” questions?? kindly share the answers with me?

Darkness_hacker99 SG

For the essay question I think I can't help you. Neutral

Let's wait for physics students to help you solve the rest of the problem. Smile

eagle SG

I'm a bit busy... so I try to explain as briefly as possible

experiment...
say need voltmeter, ammeter, and either a variable voltage supplier or a fixed voltage supply with a potentiometer to vary the input voltage

Use a few voltages (>6), and record the corresponding current values
Plot graph

sketch graph
Think a bit. power increase -> resistance increase for lamp
R = V/I
so u know V increase more proportionately than I

Hence, if you plot V-I graph, graph will curve upwards
if you plotted I-V graph, graph will curve downwards

eagle SG

experiment same as above

sketch same method as above

for more info, look at here:

http://www.patent-invent.com/electricity/inventions/resistance.html

amusing_dick SG

ok another question here.

A wire of length L and cross sectional area of A has a resistance of 18ohms
calculate the resistance for a wire of same resistance with a length of 2L and 2A.
answer provided is 12ohm... couldn't get it. Sad Rolling Eyes
kindly show the steps arriving at 12ohms for me? Wink

eagle SG

think answer wrong.

resistance for a wire of same resistance sounds wrong too...

Darkness_hacker99 SG

Can you double check the answer provided? Smile

amusing_dick SG

Originally posted by eagle:

think answer wrong.

[b]resistance for a wire of same resistance sounds wrong too...[/b]

ok lets say if its the same material but the focus point is on the increase of length to 2L and cross sectional area to 2A.

eagle SG

I'm sure you know the answer

R = pL/A

increase length to 2L and area to 2A will of course have the same effect.... still 18 ohms... that was why I said the answer given may be wrong...

amusing_dick SG

ok my lesson learnt is boycott shinglee TYS ans support only SAP.

eagle SG

SAP is what?

I thought is support only Homework Forum Crying or Very sad

amusing_dick SG

its Singapore Asian Publishing which produce better tys booklets than other tys producers out there like shinglee and dyna..

tanjun SG

Originally posted by eagle:

think answer wrong.

[b]resistance for a wire of same resistance sounds wrong too...[/b]

I guess the word should be resistivity.

Darkness_hacker99 SG

Yar. Smile