# Why can the image of the building be seen inside the plane mirror ? P.43.

## Presentation on theme: "Why can the image of the building be seen inside the plane mirror ? P.43."— Presentation transcript:

Why can the image of the building be seen inside the plane mirror ? P.43

Light ray from the object enter the eye. (Directly or indirectly) Object can be seen Object P.43

Luminous objects Emit their own light P.43

Non-luminous objects Can be seen when light is reflected from luminous objects P.43

Light travels in straight line Light ray Line along which light energy is transferred P.43

Light beam Cone of light Pencil of light P.43

Incident ray Reflected ray Refracted ray P.43

Incident ray Reflected ray Refracted ray Transparent object P.43

Incident ray Reflected ray Refracted ray Opaque object P.43

All the light is absorbed Black Reflection P.43

All the light is reflected White Absorption P.43

Ray box P.43

Experiment : Laws of reflection 0o0o Normal Angle of reflection Angle of incidence P.43

What is the relation between i & r ? ir 0o0o 15 o 30 o 45 o 60 o 75 o ir 0o0o 0o0o 15 o 30 o 45 o 60 o 75 o P.43

Plane mirror Incident ray Reflected ray Normal i r P.43

Laws of reflection Incident ray, reflected ray & normal lie on the same plane  i =  r P.43

30 o What is r ? 60 o 30 o P.43 Q1(a)

55 o What is r ? 35 o 55 o P.43 Q1(b)

45 o P.44 Q2

60 o 50 o 40 o 50 o 70 o 20 o P.44 Q2

20 o 40 o P.44 Q2

30 o 65 o 25 o 65 o 85 o 5o5o 5o5o P.44 Q2(b)

45 o P.44 Q2(c)

70 o 10 o P.44 Q5 20 o 60 o

Smooth surface P.45

Regular reflection P.45

Rough surface Light rays are scattered P.45

Diffuse reflection P.45

Light rays Copy the shape of the object Image P.45

Real image Image is formed on the screen P.45

Virtual image Image is formed behind the screen P.45

Real image Converge at the position of the image Light rays pass through the real image Real image can be formed on the screen P.45

Virtual image Diverge from the position of the image Light rays do not pass through the real image Virtual image cannot be formed on the screen P.45

P.45 Q1

P.45

uv Experiment : Locating an image by ray tracing What is the relationship between u & v ? P.45

Two triangles are congruent uv Same areas & same bases Same heights P.45

Image formed by a plane mirror Object distance u = image distance vSame size UprightVirtual P.45

P.46 Q1 B D C A

P.46 Q2

1.4m 0.1m 1m 0.05 + 0.7 m P.46

0.7m 0.05m Two pairs of Congruent triangles The minimum size of the mirror is half of the height of the lady P.46

1m 1.6m 0.8m Two triangles are similar The minimum length of the mirror is half the height of the girl P.46

P.46 Q1(a) 2 m/s

P.46 Q1(b) 4 m/s 2 m/s

P.47 Q2(a) 2.3 m (b) We can see the chart behind the boy.

Left hand Right hand Lateral inversion P.49

Left & right hand sides are interchanged P.49

What will be seen in the rear mirror? P.49

90 o 3 images I 1 & I 2 are laterally inverted I 12 or I 21 are not P.49

M2M2 M1M1 I2I2 I 12 I1I1 O I 21 I 12 & I 21 overlap I 2 is the image of O on M 2 I 1 is the image of O on M 1 I 12 is the image of I 1 on M 2 I 21 is the image of I 2 on M 1 I 12 is formed by 2 reflection of light therefore no lateral inversion P.49

I 212 M2M2 M1M1 60 o I 121 & I 212 overlap 5 images are formed I 12 & I 21 are not laterally inverted P.49

Infinite number of images P.49

M2M2 M1M1 5cm 2cm P.49

Dressing P.49

Decoration P.49

Space seems to be larger P.49

The image of the bear can be seen indirectly P.50

Bus driver can see passengers on the top deck P.50

I2I2 I1I1 O M2M2 M1M1 10cm 20cm P.50

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