Q22 of 58 Page 1

(a) Define the following terms in the context of spherical mirrors:

(i) Pole (ii) Centre of curvature


(iii) Principal axis (iv) Principal focus


(b) Draw ray diagrams to show the principal focus of a:


(i) Concave mirror (ii) Convex mirror


(c) Consider the following diagram in which M is a mirror and P is an object and Q


Is its magnified image formed by the mirror?



State the type of the mirror M and one characteristic property of the image Q.

(a)


 



 


(i) Pole- The centre of the spherical mirror is called pole represented by P.


 


(ii) Centre of curvature- it is the centre of the hollow sphere of glass of which the mirror is the part. Represented by C, the centre of curvature of concave mirror is in front but the centre of curvature of convex mirror is at its back.


 


(iii) Principal axis- of a spherical mirror is the straight line joining the centre of curvature and pole of the mirror. The principal axis is normal to the mirror at the pole.


 


(iv) Principal focus- it is a point on the principal axis of the spherical mirror at which the light rays which are parallel to the principal axis converge or appear to diverge after reflection.


 


(b) Ray diagrams of principal focus:


 


(i) Concave mirror: The principal focus of concave mirror is the point on the principal axis to which all the light rays which are parallel and close to axis converge after reflection. Thus, concave mirror has a real principal focus and it lies in front of the mirror.


 


(ii) Convex mirror: In a convex mirror, the reflected rays do not actually pass through the focus (F), they appear to diverge. Thus, a convex mirror has a virtual principal focus situated behind the mirror.


 




(c) The mirror used in the given diagram is a concave spherical mirror. Image formed (Q) is virtual, erect and magnified.




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20

(a) Write the functions of the following parts in human female reproductive system:

(i) Ovary


(ii) Oviduct


(iii) Uterus


(b) Describe the structure and function of placenta.

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What is meant by speciation? List four factors that could lead to speciation. Which of these cannot be a major factor in the speciation of a self-pollinating plant species. Give reason to justify your answer.

 23

(a) Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.

(b) In the above ray diagram mark the object-distance (u) and the image-distance (v) with their proper signs (+ve or -ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.


(c) Find the power of a convex lens which forms a real, and inverted image of magnification -1 of an object placed at a distance of 20 cm from its optical centre.

 24

(a) Write the function of each of the following parts of human eye:

cornea; iris; crystalline lens; ciliary muscles


(b) Millions of people of the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organize a campaign in your neighbourhood in order to create awareness about this fact. you are asked to participate in this mission how would you contribute in noble cause?


(i) State the objective of organizing such campaigns.


(ii) List two arguments which you would give to motivate the people to do their eyes after death.


(iii) List two value which are developed in the persons who actively participate and contribute in such programmes.