S3 Phy Images formed by concave and convex lens

Which of the followings is/are correct?

• F is focal length

• F is principal focus

• O is optical centre

• The lens in the diagram is a convex lens

Which of the followings describe the photo correctly?

• The lens in the photo are concave lens.

• The image is virtual, inverted and diminished.

• The light ray bends and hits the focus after travelling in parallel to the principal axis.

• The photo demonstrates the case of u(object distance) < 2f (focal length)

Which of the followings concerning lens formula is/are correct

• The equation is $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$ , while u is object distance, v is image distance and f is focal length.

• The focal length can be negative.

• When the image distance is minus (e.g. v=-1) the image is virtual, and when positive (e.g. v=1), the image is real.

• We cannot find the focal length using the lens formula when given the image distance and object distance

What are the steps for drawing the diagram of the images formed by concave/convex lens?

1. Mark the positions of  $F,\ F^,,\ 2F,\ and\ F^,$ 
2. Draw the object as an arrow at the position as given
3. Draw the image formed using dotted lines, if the rays bisect, draw the arrow on the intersection point on the focal plane, else trace back the image.
4. Draw the principal axis
5. Draw two rays, one passing through the optical centre and the other parallel to the pricipal axis, and the other depending on the lens.

•  $1>4>5>3>2$  

•  $2>4>1>5>3$  

•  $4>1>2>5>3$  

•  $5>4>1>2>3$  

Which of the construction rules is/are Incorrect?

• When a light ray passes through a convex lens parallel to the principal axis, it hits the principal focus.

• When a light ray passes through a convex lens from the principal focus $F^,$ , it bends parallel to the principal axis.

• When a light ray passes through the optical centre, the direction remains unchanged.

• The images formed by concave lens are always real, inverted and magnified.

Which of the following descriptions is correct?

• a is the symbol for concave lens and b is the symbol for convex lens

• Only a can be used when drawing concave and convex lens.

• a is the symbol for convex lens and b is the symbol for concave lens

• Only b can be used when drawing concave and convex lens.

Which of the followings concerning concave lens is correct?

• Concave lens converge light

• Light rays are bent towards the principal axis when it passes through concave lens and comes in parallel.

• The light rays will always intersept after passing through concave lens.

• ALL the images formed by concave lens are virtual, erect and diminished.

What lens are the photo showing?

• They are all concave lens

• They are all convex lens

• First three are convex lens and the last one is concave lens

• First three are concave lens and the last one is convex lens

How can you calculate linear magnification (m)?

•  $m=\frac{focal\ length}{image\ dist\ ance}$  

•  $m=\frac{height\ of\ image\ \left(image\ size\right)}{height\ of\ object\ \left(object\ size\right)}=\frac{h_i}{h_o}$  

•  $m=\frac{object\ dist\ amce\ \left(u\right)}{image\ dist\ ance\ \left(v\right)}$  

•  $m=\frac{image\ dist\ ance}{object\ dist\ ance}=\frac{v}{u}$  

Diamond has a refractive index of 2.42, and water has a refractive index of 1.33, diamond is an (a)   medium. (Compare the refractive index)