OPTICS 1 2

1. Name rays 1&2, and the orange one2. Where is the angle of INCIDENCE?3. State the 2 laws of reflection

OPTICS

air

Water

Air

1. Name rays 1&2, and the top orange one2. Where is the angle of INCIDENCE?3. Describe how the 1st refracted ray has bent.4. Describe how the 2nd refracted ray has bent.5. This refractor is called?????

1

2

air

Water or Glass

Air

OPTICS

1. Name rays 1&2, and the orange one2. Where is the angle of INCIDENCE?3. Describe how ray 1 bent going from water to air from air to water4. Why does it take this line?5. This refractor is called????? 6. When ray 1 strikes at a slightly larger angle, refraction tries to travel along the surface7. What is this angle called?8. Draw this “refraction” ray9. Draw the actual ray.10. What is this actually called

1

2

OPTICS

1. Name rays 1&2, and the orange one

Refracted rays can be identified and recorded using pins

The eye above would see that the pins on the REFRACTED ray are in line with the pins on the INCIDENT ray

OPTICS – Predicting Refraction Angle

• See page 172: Snell’s Law for transparent solids:

• From p 153 some REFRACTIVE INDEXES:crown glass n = 1.52, acrylic (perspex) n = 1.49, water n = 1.33

• The CRITICAL ANGLE (c) is the angle in water, glass etc that makes the angle in air = 90°, and makes sin i = 1

• From p 154 Some CRITICAL ANGLES crown glass c = 41°, acrylic (perspex) c = 42°, water c= 49°

AIR

GLASS

OPTICS

Give the symbol for the NORMAL RAY, the Refractive Index the Critical Angle`

When angle in AIR = 90°, the angle in Glass is called the CRITICAL ANGLE

Sin 90 = 1 so

AIR

GLASS

OPTICS

Which ray meets the normal at the CRITICAL ANGLE`

Air

Glass

Air

OPTICS

1. Name rays 1&2, and the orange ones2. Where is the angle of INCIDENCE?3. Describe how ray 1 bent going from air to glass4. Why does it take this line?5. This refractor is called?????

1 2ROYGBIV

Principal Axis

Focal length

OPTICS

1. Two Triangular Prisms are like a convex lens2. The Principal axis is. . . . .3. Rays parallel to the Principal Axis meet at______________

Principal Axis

_ _ _ _ _ _ to_ _ _ _

Focal length

OPTICS

1. Two Triangular Prisms are like a convex lens2. A convex lens is thick at the middle and thin at the edge,

FOCUS

Principal Axis

_ _ _ _ _ _ to_ _ _ _

Focal length

OPTICS Ray Writing Rule 1

There are 3 standard rays for finding image positions; any pair will do.

1. A ray from an object travels straight through to image positionwhen it crosses the centre line of lens AND principal axia

FOCUS

Focal length

OPTICS Ray Writing Rule 2

2. FROM an object, A ray PARALLEL to the principal axis bends THROUGH focus to go to image position. The image where the rays meet

FOCUS FOCUS

Focal length

OPTICS Ray Writing Rule 3

3. from an object, A ray THROUGH focus bends TO BE PARALLEL to the principal axis to go to image position.

FOCUS FOCUS

OBJECT

IMAGE

Focal length

OPTICS Virtual Image from Convex Lens

Object is between lens and focus. Same rules for lines to lens when beyond 2f. Image is VIRTUALDotted arrows show where rays APPEAR to have come from

OPTICS• Text book, page 174• Problems 2, 3,4,5, 6.

• Page 157• Problems 1,2,3

• Page 159• Problems 1,2,3

• Mr Graham 2012