Perform the following activity and learn for yourself. Take two cloth pieces of the same size, roughly half a metre aquare each. One of these should be from natural fibre.the other could be a synthetic fibre. You can take help of your parents in selecting these pieces. Soak the pieces in different mugs each containing the same amount of water. Take the pieces out of the containers after five minutes and spread them in the sun for a few minutes. Compare the volume of the water remaining in each container. Do synthetic fabrics soak less/more water than the natural fabrics? Do they take less/more time to dry? What does this activity tell you about the characteristics of the synthetic fabrics? Find out from your parents about the durability, cost and maintenance of these fabrics, compared to the natural fabrics.

From the first law of thermodynamics derive the relation Cp-Cv =R whwre the symbols have their usual menaings .

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of of each test tube?

Two particles-one of mass m1, and the other of mass m2, carry equal charges. After being accelerated through the same potential difference they enter a region of uniform magnetic field and describe circular paths of radius (r_1) , and (r_2) , respectively. Find the ratio of their masses.

State the underlying principle of a potentiometer. Write two factors on which the sensitivity of a potentiometer depends. In the potentiometer circuit shown in the figure, the balance point is at X. State giving reason, how the balance point is shifted when (a) resistance R is increased (b) resistances is increased, keeping R constant?

(Attempt any ten of the following questions) Define one coulomb charge. Two point charges at a distance r in air exert a force F on each other. At what distance will these charges experience the same force F in a medium of dielectric constant k?

Two organ pipes one open at both ends,and the other open at one end only give their fundamental noteswhose frequencies differ by 25 vibration per second.The length of the open pipre is 96 cm.Calculate the length of the closed pipe if the velocity of sound in air is 330 m(s)^-1 .

Two circular coils X and Y having radii Rand R/2 respectively are placed in horizontal plane with their centres ccinciding with each other. Coil X has a current I flowing through it in the clockwise sense. What must be the current in coil Y to make the total magnetic field at the common centre of the two coils zero? With the same currents flowing in the two coils, if the coil Y is now lifted vertically upwards through a distance R what would be the net magnetic field at the centre of coil Y?

From Borjhar Air Port of Guwahati two aeroplanes took off simultaneously, one towards the east with the speed of 720 km. per hour and the other towards the west with the speed of 880 km. per hour. After how many hours will the two aeroplanes be 4000 km. apart? Solve the problem by forming an equation.