a)

A student wants to use a lens and project the picture of a candle flame onto thewalls of the school lab.

(i)Which type of lens should be used and why?

(ii) How far away from the lens focal length "F" should he set the candle flame in order to getthe enlarged picture on the wall?

(iii) Draw a ray diagram to illustrate how the image is created in each circumstance.

(iv) Is it possible for him to reflect a diminished image of the candle flame onto the same wallusing this mirror? If the answer is yes, explain how; if the answer is no, explain why.

 

                                                                                           OR

 

b)

(a)Give definitions for the following concepts in relation to spherical mirrors:

(i) pole

(ii) centre of curvature

(iii) principal axis

(iv) principal focus

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

(i) Concave mirror

(ii) Convex mirror

(c)Consider the following diagram in whichis a mirrorandis an object and Q is its𝑀𝑃enlarged image created by the mirror.
Mention the type of mirror M and one characteristic property of the image.𝑄

 

a)

(i) He should use a convex lens as it forms real images.
(ii) He should place the candle flame between $F$ and $2 F$ (the focus and centre of curvature of the lens) to get the magnified image on the wall, while the diminished image is obtained when the object is located at a distance greater than $2 F$.
(iii) The ray diagram for the formation of the magnified image is shown below:

The ray diagram for the formation of the diminished image is shown below.

(iv) Yes, he can use a concave mirror in this case, also. A diminished image is formed if thecandle is placed beyond C.

                                                                                                  OR

b)

(a) Centre of curvature: It is the centre of the sphere of a glass of which the mirror is a part. The letter $C$ represents the centre of curvature. The principal axis of a spherical mirror is the straight line joining the centre of curvature and the pole of the mirror.
Principal focus: The midpoint of $C P$ is called focus $(F)$.
The pole of a spherical mirror is the centre of the reflecting surface of the spherical mirror.

b) 

i) Concave mirror

(ii) Convex mirror

(c) We will draw the ray diagram first and try to identify the nature of the mirror.

The object is kept between the focus and the pole of the mirror, and as we can see when wedraw a ray parallel to the principal axis and a ray passing through the pole of the mirror andwhen we extend the reflected rays to meet at a point where is image is formed, we can seethat the nature of the mirror is converging as the incident rays are converging to a point in theother side of the mirror to form a virtual object.Therefore the mirror is a concave mirror