1Q2) d..
A blackbody of temperature T is inside chamber of T0 temperature initially, Sun rays are allowed to fall from a hole in the top of chamber. If the temperature of blackbody (T) and chamberT0 remains constant, then which of the following is not correct about 'black-body'?
It will absorb less radiation
It will absorb more radiation
It will emit more energy
It will emit energy equal to energy absorbed by it
Ans is (a)
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13 Answers
42) In forced oscillation of a particle, the amplitude is maximum for a frequency w1 of the force, while the energy is maximum for a frequency w2 of the force, then
(A) w1 = w2
(B) w1 < w2
(C) w2 < w1 when damping is small and w2 > w1 when damping is small
(D) w2 > w1
Ans (A)
43) A space lab is revolving round the earth at a height 3R from earth's surface where R is radius of the earth. The time-period of a seconds pendulum in this lab is
Option
zero
infinity
2 sec
9.8 sec
Ans is infinity
44) As atomic number A of nucleus increa-ses,
the 'binding energy per nucleon' (B) increases when neutron-proton ratio' increases
initially the ratio n/p is unity
initially n/p increases and later decreases
initially B decreases and then increases
Ans B
4MATHS
Regression equation of Y on X is 3x + 4y - 18 = 0. The value of bxy is
(a) - 1/2
(b) - 3 /4
(c) 5/6
(d) 4/18
4@Ray :ans for 1 st one I've posted (but i want the reason)
2) u r wrong check the ans i posted
1but wont the g0 there be g/16 sandipan,given that h=3R?
g0=g(1+h/R)-2=g(1+3)-2=g/16
so time period should be 4 times that os a seconds pendulum on the face of earth,that is 8 s.
11ya arka....answered in a hurry...sry...deleted the post
12
.amplitude is maximum when freq. of d external frequency is equal to the natural freq. of the body, i.e, at resonance
.....and energy directly varies with amplitude, hence w1=w2..
[It's der in syllabus]
13.has to be infinity,
Hint:weightlessness in a satellite...the satellite is revolving,
39Regression equation se coefficient nikaalna...I had posted all that info in a BITS math thread.
http://www.targetiit.com/iit-jee-forum/posts/maths-15931.html
Basically the slope of the regression line is the regression coefficient bxy.
bxy = -3/4 here.
It should be byx waise....bxy is for regression line of X on Y. This is regression line of Y on X. Both b's are different.
1) mein do we have to use Stefan's law?