Q. a metre scale made of steel is calibrated at 20⁰C to give correct readin. Find d distance b/n 50 cm mark and 51 cm mark if d scale is used at 10⁰C. Coefficient of linear expansion of steel is 1.1 *10^-5/⁰C.

ans is1.00011 cm.

if u get dis ans plz explain me d logic.

i got .999. as it should contract wen temp decreases.

i remebber the sum.

the ans ans is1.00011 cm.

the logic is :

consider 2 pegs b/w 50 and 51 cm

At 20 degree , it gives correct distance 1 cm.

at 10 degree , the scale is reduced so the dist. b/w the pegs if measured will be greater than 1.

Actually Bipin Bhaiya ( expert ) helped me.

It was long ago , april last yr.

edited.

Yes. I m right.

It is Q. 11 of page 12  vol II of hcv. ( just checked )

I made the same mistake which u made now.

Remember the distance between 2 columns ( say ) at 50 cm and 51 cm is fixed. U r not shifting the columns.

Now when measured with a scale at 20 degree , this distance comes out as 1 cm. 

so when measured  with a scale at 10  degree , the scale i, e measuring instrument , is reduced.

This distance  then comes out as 1.00011 cm by this faulty scale.

listen when u decrease the temperature, the scale contracts meaning the reading will be more.

if it was showing a lenght of 5 b4 now it shuld show more than that..

got the logic?.. so now apply  Length(read)=lenght(actual) *(i+alpha *change in temp)

tell me if u still didnt get i'll solve it for u

This Q reminds me my journey  thro Verma which is yet to be finished.

It was april 2007.

Unlike others, I started with Heat, expansion, calorimetry.

I first thought there is some mistake in the result. But others say, it is a no - mistake book. So I tried here and there. Also posted in goiit.

This Q reminds me the memory  and thanks for that.

P.S. Don't know, whether I should hav said it here.

I agree with zark...

As the scale contracts...the pegs also comes closer....so if we r measuring any rod with dat same scale at 10C....we get an increased length shown by the faulty scale.

actually first even i made d same mistake but got it later...!!!