3c. Thin Converging Lenses

Question 1

Focal length (f)

Definition

Answer 1

The distance between the optical center (C) and the principal focal point (F)

Question 2

Difference between a thicker converging lens and a thinner converging lens

Answer 2

Thicker converging lens: larger angle of incidence => light bends more => shorter focal length
Thinner converging lens: smaller angle of incidence => light bends less => longer focal length

Question 3

Object is at Infinity (u=∞)

Position & characteristics of image through converging lens + Example

Answer 3

Position: Image is at F (v = f) (opposite side of the lens)
Characteristics: Diminished, real, inverted

Used in telescope

Question 4

Object is further than 2F (u > 2f)

Position & characteristics of image through converging lens + Example

Answer 4

Position: Image is between F and 2F (f < v < 2f) (opposite side of the lens)
Characteristics: Diminished, real, inverted

Used in camera

Question 5

Object is at 2F (u = 2f)

Position & characteristics of image through converging lens + Example

Answer 5

Position: Image is at 2F (v = 2f) (opposite side of the lens)
Characteristics: Same size, real, inverted

Used in photocopier making same-sized copy

Question 6

Object is between F and 2F (f < u < 2f)

Position & characteristics of image through converging lens + Example

Answer 6

Position: Image is further than 2F (v > 2f) (opposite side of the lens)
Charcteristics: Magnified, real, inverted

Used in projector

Question 7

Object is at F (u = f)

Position & characteristics of image through converging lens + Example

Answer 7

Position: Image is at infinity (same side of the lens)
Characteristics: Magnified, virtual, upright

Used in spotlight

Question 8

Object is between C and F (u < f)

Position & characteristics of image through converging lens + Example

Answer 8

Position: Image is behind object (same side of the lens)
Characteristics: Magnified, virtual, upright

Used in magnifying glass