Predicting Images in

Convex and Concave Lenses

When the object is located at twice the focal length (2F)

Any incident ray parallel to the principal axis will……

When the object is located at twice the focal length (2F)

Any incident ray parallel to the principal axis will refract through the Focus.

When the object is located at twice the focal length (2F)

Any incident ray passing through the Focus will……

When the object is located at twice the focal length (2F)

Any incident ray passing through the Focus will reflect parallel to the principal axis.

When the object is located at twice the focal length (2F)

Any incident ray passing through the Optical Centre will……

When the object is located at twice the focal length (2F)

Any incident ray passing through the Optical Centre will pass undeviated (straight through).

When the object is located at twice the focal length (2F)

image's characteristics• At 2F• Inverted• Same size• Real

When the object is located at twice the focal length (2F)

image's characteristics• Location• Orientation• Size• Type

When the object is located between twice the focal length (2F) and the Focus (F)

Any incident ray parallel to the principal axis will……

When the object is located between twice the focal length (2F) and the Focus (F)

Any incident ray parallel to the principal axis will refract through the Focus.

When the object is located between twice the focal length (2F) and the Focus (F)

Any incident ray passing through the Focus will……

When the object is located between twice the focal length (2F) and the Focus (F)

Any incident ray passing through the Focus will refract parallel to the principal axis.

When the object is located between twice the focal length (2F) and the Focus (F)

Any incident ray passing through the Optical Centre will……

When the object is located between twice the focal length (2F) and the Focus (F)

Any incident ray passing through the Optical Centre will pass undeviated (straight through).

When the object is located between twice the focal length (2F) and the Focus (F)

image's characteristics• Beyond 2F• Inverted• Larger• Real

When the object is located between twice the focal length (2F) and the Focus (F)

When the object is located at the Focus (F)

Any incident ray parallel to the principal axis will……

When the object is located at the Focus (F)

Any incident ray parallel to the principal axis will refract through the Focus.

When the object is located at the Focus (F)

Any incident ray passing through the Focus will……

When the object is located at the Focus (F)

Any incident ray passing through the Focus will travel parallel to the lens and not intersect it.

When the object is located at the Focus (F)

Any incident ray passing through the Optical Centre will……

When the object is located at the Focus (F)

Any incident ray passing through the Optical Centre will pass undeviated (straight through).

When the object is located at the Focus (F)

When the object is located at the Focus (F)

Where is the image? The rays appear to be parallel.

If the rays start on part of the object slightly closer to 2F, they are not parallel. They converge slightly, ……

When the object is located at the Focus (F)

Where is the image? The rays appear to be parallel.

When the object is located at the Focus (F)

If the rays start on part of the object slightly closer to 2F, they are not parallel. They converge slightly, then they will meet far away. The Images Characteristics would be:

• Very Far Away (at ∞) • Inverted• Very Large • Real

Where is the image? The rays appear to be parallel.

When the object is located at the Focus (F)

If the rays start on part of the object slightly closer to O, they are not parallel. They diverge slightly, ……

Where is the image? The rays appear to be parallel.

When the object is located at the Focus (F)

If the rays start on part of the object slightly closer to O, they are not parallel. They diverge slightly, then they will meet far away in the opposite direction. The image's characteristics would be:

• Very Far Away (at ∞) • Upright• Very Large • Virtual

When the object is located at the Focus (F)

When the object is located between the Focus (F) and the Optical Centre (O)

Any incident ray parallel to the principal axis will……

When the object is located between the Focus (F) and the Optical Centre (O)

Any incident ray parallel to the principal axis will refract through the Focus.

When the object is located between the Focus (F) and the Optical Centre (O)

Any incident ray moving in a direction that is the same as if it had passed through the Focus will……

When the object is located between the Focus (F) and the Optical Centre (O)

When the object is located between the Focus (F) and the Optical Centre (O)

Any incident ray moving in a direction that is the same as if it had passed through the Focus will refract parallel to the principal axis.

Any incident ray passing through the Optical Centre will……

When the object is located between the Focus (F) and the Optical Centre (O)

any incident ray passing through the Optical Centre will pass undeviated (straight through).

When the object is located between the Focus (F) and the Optical Centre (O),

Where is the image? The rays diverge.

When the object is located between the Focus (F) and the Optical Centre (O)

If the rays diverge, the image is where they appear to meet in the opposite direction. Then the image's characteristics would be:

• Same Side as object • Upright• Larger • Virtual

When the object is located between the Focus (F) and the Optical Centre (O)

When the object is located beyond 2F

If the rays diverge, the image is where they appear to meet in the opposite direction. The image’s characteristics would be:

• Same Side as Object • Upright• Smaller • Virtual

When the object is between 2F and F

An incident ray parallel to the principal axis will……

When the object is between 2F and F

When the object is between 2F and F

An incident ray parallel to the principal axis willrefract as if it had passed through the principal Focus.

When the object is between 2F and F

An incident ray moving toward the Secondary Focus will

When the object is between 2F and F

An incident ray moving toward the Secondary Focus will refract parallel to the principal axis.

When the object is between 2F and F

An incident ray passing through the Optical Centre will……

When the object is between 2F and F

An incident ray passing through the Optical Centre will pass undeviated (straight through).

When the object is between 2F and F

Where is the image? The rays diverge.

When the object is between 2F and F

If the rays diverge, the image is where they appear to meet in the opposite direction. The image’s characteristics would be

• Same Side as Object • Upright• Smaller • Virtual

When the object is between F and O

An incident ray parallel to the principal axis will……

When the object is between F and O

When the object is between F and O

An incident ray parallel to the principal axis willrefract as if it had passed through the principal Focus.

When the object is between F and O

An incident ray moving toward the Secondary Focus will……

When the object is between F and O

An incident ray moving toward the Secondary Focus will refract parallel to the principal axis.

When the object is between F and O

An incident ray passing through the Optical Centre will……

When the object is between F and O

An incident ray passing through the Optical Centre will pass undeviated (straight through).

When the object is between F and O

Where is the image? The rays diverge.

When the object is between F and O

If the rays diverge, the image is where they appear to meet in the opposite direction. The image’s characteristics would be:

• Same Side as Object • Upright• Smaller • Virtual

5) If the object IS MOVED far beyond twice the focal length (2F) of a CONVEX (CONVERGING) LENS, the image will move TOWARD the FOCUS.

6) If the object IS MOVED close toward the Focus of a CONVEX (CONVERGING) LENS, the image will move FAR BEYOND 2F.

7) In order to produce a VIRTUAL IMAGE with a CONVEX (CONVERGING) LENS, the object must be placed BETWEEN the FOCUS (F) AND the Optical Centre (O).

8) In order to produce a REAL IMAGE with a CONVEX (CONVERGING) LENS, the object must be placed BEYOND the FOCUS (F).

Predicting Images in a Convex Lens

9) In order to produce an ERECT IMAGE with a CONVEX (CONVERGING) LENS, the object must be placed BETWEEN the FOCUS (F) AND the Optical Centre (O).

10) In order to produce the LARGEST IMAGE POSSIBLE with a CONVEX (CONVERGING) LENS, the object must be placed AT the FOCUS.

Predicting Images in a Convex Lens

4) If the object IS MOVED far beyond twice the focal length (2F) of a CONCAVE (DIVERGING) LENS, the image will move TOWARD the FOCUS.

5) If the object IS MOVED close toward the Focus of a CONCAVE (DIVERGING) LENS, the image will move TOWARD the LENS.

6) In order to produce a VIRTUAL IMAGE with a CONCAVE (DIVERGING) LENS, the object can be placed ANYWHERE.

7) In order to produce a REAL IMAGE with a CONCAVE (DIVERGING) LENS, the object must be placed – IT CAN’T BE DONE.

Predicting Images in a Concave Lens

8) In order to produce an ERECT IMAGE with a CONVEX (CONVERGING) LENS, the object can be placed ANYWHERE.

9) In order to produce the LARGEST IMAGE POSSIBLE with a CONVEX (CONVERGING) LENS, the object must be placed CLOSE TO THE LENS.

Predicting Images in a Convex Lens