Q23 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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21

A green stemmed rose plant denoted by GG and a brown stemmed rose plant denoted by gg are allowed to undergo a cross with each other.

(a) List your observation regarding


(i) Colour of stem in their F1 progeny


(ii) Percentage of brown stemmed plants in F2 progeny if F1 plants are self-pollinated.


(iii) Ratio of GG and Gg in the F2 progeny.


(b) Based on the findings of this cross, what conclusion can be drawn?


 22

The diagram given below show an Object O and its image I.


Without actually drawing the ray diagram, state the following:


(i) Type of lens (Converging / Diverging)


(ii) Name two optical instruments where such an image is obtained.


(iii) List three characteristics of the image formed if this lens is replaced by a concave mirror of focal length 'f and an object is placed at a distance 'f/2' in front of the mirror.


 24

(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

Write balanced chemical equations to explain what happens, when

(i) Mercuric oxide is heated.


(ii) Mixture of cuprous oxide and cuprous sulphide is heated.


(iii) Aluminium is reacted with manganese dioxide.


(iv) Ferric oxide is reduced with aluminium.


(v) Zinc carbonate undergoes calcination.


OR


(i) By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound.


(ii) Ionic compounds are solids. Give reasons.


(iii) With the help of a labelled diagram show the experimental set up of action of steam on a metal.