17-03-09 Searle's Method

spirit level is a device of wood filled with spirit at the center, with some space left. it is used to check the slope of a plane.

if the bubble in the device is at center then the plane is perfectly horizontal, if it is towards left or right then the surface has a slope

oh yes............i saw that once in cartoon[3][3].......maybe mickey mouse....[12][12][9]

We conduct an experiment on determination of young's modulus by Searle's method.
The micrometer attached has a pitch of 1 mm. It has 100 divisions on the circular scale.
On addition of additional mass 100 g , the screw had to be turned just more than 10 times to attain balance. The change in the circular scale reading was 92.

Q49) What is the extension of the wire due to the additional mass? (Ans in mm)
a) 10.92
b) 9.92
c) 10.08
d) None of these

Q50) What is the slope of the graph plotted in this experiment? (Assume the change in length to be 10 mm)
The units of the graph are in SI units!
a) 10-2
b) .1
c) 1
d) None of these

yeah tapan good time to ask the ques 4m the test[1][4]

49. a
50. b wat r the ans ,,,

post d ans plz...

tapan giv the ans of ur ques .....

PRECISELY DUDE, wer my Answers BUT [2] both hav bn marked as wrong...........

NISHANT SIR, Can u pl. xplain the reasoning/working 4 these questns.....

[23] [24] [27]

u have to do all questions of error like that ........

for eg.
x=aⁿb^m
=>Δx/x=±(nΔa/a +mΔb/b)

result is same even if x=a/b

Object

Measure the thermal conductivity of Copper using the Searle's bar method.

SAFETY WARNING

This experiment uses steam heating. Be careful to avoid touching the hot surfaces of the steam generator, tubing and the Searle's bar apparatus. Make sure that the steam outlet tube from the apparatus goes to a sink.

Apparatus

Constant-head apparatus, measuring cylinder, stop watch, Searle's apparatus, steam generator, four thermometers T1, T2, T3, T4, Vernier callipers.

T1 and T2 measure the temperature at points on the bar, T3 and T4 measure the temperature of water entering and leaving the spiral C.

Method

Adjust the constant-head device to give a steady flow of water through the coiled tube.
Pass steam from the steam generator through the steam chest. wait until the thermometers have reached a steady state (i.e. no significant increase or reduction of temperature for 10 minutes).
Measure T1, T2, T3 and T4.
Measure the rate of water flow through the spiral by measuring the amount of water (m) collected in the measuring cylinder in a given time (t). Collect approximately 1 litre.
Using Vernier callipers, measure the diameter of the bar D and the distance d between the thermometers T1 and T2.
Theory

Assuming no loss of heat along the bar, it can be shown that:

where:

Q is the heat supplied to the bar in time t,

A is the cross-sectional area of the bar,

dT is the difference in temperature between two points in the bar dx apart,

k is the coefficient of thermal conductivity of the bar.

The heat Q warms up a mass m (in kilograms) of water from temperature T4 to T3 according to the formula:

where c is the specific heat capacity of water (c = 4190 J kg-1 K-1).

Using: , (d in metres), and (A in metres squared) we obtain:

(in W m-1 K-1).
Calculate k and the error in k - see below.

Quote your final result for the thermal conductivity as k k with appropriate units.

Error Calculation

There is an error in assuming that no heat lost along the bar, but no correction has been made for this, although this will obviously affect the values of T2 and T1.
The absolute error in each of the temperature differencesandis the sum of the absolute errors in reading the two thermometers.
Errors in m arise from errors in determining the mass of water collected.
Errors in the time t depend on the accuracy of the stop-watch.
Errors in measuring with the Vernier calliper are at least 0.05 mm, but may be bigger (estimate how precisely you can measure D and d).
The fractional error in k is given by: , hence determine the absolute error Dk.

Oi maine subtract kaha kiya hai BHAI (ankit)?????"

add hi to kiya hai har jagah par.....

u are correct ... dude the error percent is 11.25% ...
11.25 % 2*10^11 is 2.25 * 10^10 .. .. only option b is near to it . .so it is the correct answer ... :)

ha ha .. what a folly ..
2.25 * 10^10 or 0.225 * 10^11
final ans
(2.0 ± 0.225) * 10^11
but error is present in the doubtful digit ... so error has 1 digit that is (2.0 ± 0.2) * 10^11

i got it tapan dude ... [50]

OH YEAH!!!!!!!!

NICE ONE BUDDY

SIR,

REFERENCE TO : the type of questions wich cud b askd,
will they b similar to the ones asked in FT1?

matlab : LC/PITCH ya fir reading ya SLOPE or INTERCEPT

hehe ...

yeh phy ka hai .. :P

Sir,
Apart frm the ones that r bold others general and can b easily known simple applctn of concepts....

I needed some help in the "BOLD" topics.......

This thread shall help my cause,

Can u/ne1 pl. (ONLY IF POSSIBLE) provide me some literature for the 3 marked topics in accordance with JEE

IT wud b a gr8 HELP.....

Thnx [1]

hey thanks tapan for asking on my behalf as well....
hey everyone tapan and i are really good friends and it gives me bitter-sweet pain to tell u that he wont accept anything untill u offer it to me too... [4][4]

SORRY TAPAN FOR HARRASING U .....but i really need that help if my heart is to be spared all the bother it is going through now