Q24 of 30 Page 1

Give reasons for the following:

(i) There is either a convergence or a divergence of magnetic field lines near the ends of a current carrying straight solenoid.


(ii) The current carrying solenoid when suspended freely rests along a particular direction.


(iii) The burnt out fuse should be replaced by another fuse of identical rating.


(a) The divergence or the degree of closeness of the magnetic field lines near the ends of a current carrying straight solenoid indicates a decrease in the strength of magnetic field.

(b) The magnetic field lines that are produced by the solenoid are similar to that of the bar magnet and behave like a bar magnet. One end of it behaves like a magnetic north pole and the other end as magnetic south pole.


(c) A fuse wire works because of its lower melting point which is possible. If a fuse with larger rating is used with an appliance, the fuse wire shall not melt and hence would fail to serve the required purpose.


More from this chapter

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22

(a) State snell’s law of refraction of light.

(b) When a ray of light travelling in air enters obliquely into a glass slab, it is observed that the light ray emerges parallel to the incident ray but it is shifted sideways slightly . Draw a labelled ray diagram to illustrate it.


 23

(a) With the help of labelled ray diagram show the path followed by a narrow beam of monochromatic light when it passes through a glass prism.

(b) What would happen if this beam is replaced by a narrow beam of white light ?


OR


(a) A person is suffering from both myopia and hypermetropia.


(i) What kind of lenses can correct this defect ?


(ii) How are these lenses prepared ?


(b) A person needs a lens of power + 3D for correcting his near vision and – 3D for correcting his distant vision. Calculate the focal lengths of the lenses required to correct these defects.


 25

(a) Compare soaps and detergents on the basis of their composition and cleansing action in hard water.

(b) What happens when ethanol is treated with sodium metal? State about the behaviour of ethanol in this reaction.


(c) Draw the structure of cyclohexane.


(d) Name the following compound



26

A metal ‘M’ is stored under kerosene. It vigorously catches fire, if a small piece of this metal is kept open in air. Dissolution of this metal in eater release great amount of energy and the metal catches fire. The solution so formed turns red litmus blue.

(a) Name the metal ‘M’


(b) write formula of the compound formed when this metal is exposed to air.


(c) Why is metal ‘M’ stored under kerosene?


(d) If oxide of this metal is treated with hydrochloric acid, what would be the products?


(e) Write balanced equations for:


(i) Reaction of ‘M’ with air.


(ii) Reaction of ‘M’ with water.


(iii) Reaction of metal oxide with hydrochloric acid.


OR


(a) Write electro dot structures of Ca (At. No. 20) and O (At. No. 8).


(b) Show the formation of calcium oxide by transfer of electrons.


(c) Name the ions present in the compound.


(d) List four important characteristics of this compound.