Select the correct laws of reflection.
Answers
Answer:
The law of reflection states that the angle of reflection equals the angle of incidence—θr = θi. The angles are measured relative to the perpendicular to the surface at the point where the ray strikes the surface. ... Diffused light is what allows us to see a sheet of paper from any angle, as illustrated in Figure 3.
Explanation:
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Answer:
Explanation:
What is Law of Reflection?
Definition:
The law of reflection defines that upon reflection from a smooth surface, the angle of the reflected ray is equal to the angle of the incident ray, with respect to the normal to the surface that is to a line perpendicular to the surface at the point of contact.
The reflected ray is always in the plane defined by the incident ray and the normal to the surface at the point of contact of the incident ray.
The images produced by plane mirrors and curved mirrors can be understood by the law of reflection.
Law of reflection is defined as:
The principle when the light rays falls on the smooth surface, the angle of reflection is equal to the angle of incidence, also the incident ray, the reflected ray, and the normal to the surface all lie in the same plane.
What is Reflection of Light?
The process through which light rays fall on the surface and gets bounced back is known as a reflection of light.
Types of Reflection:
Regular Reflection:
The plane mirrors with a smooth surface produce this type of reflection. In this case, the image is clear and is very much visible. The images produced by plane mirrors are always virtual, that is they cannot be collected on a screen.
In the case of curved mirrors with a smooth surface, we can see the images of reflection either virtually or really. That is, the images produced by curved mirrors can be either real (collected on a screen and seen), or virtual (cannot be collected on a screen, but only seen).
Irregular Reflection:
Unlike mirrors, most natural surfaces are rough on the scale of the wavelength of light, and, as a consequence, parallel incident light rays are reflected in many different directions irregularly, or diffusely. Hence, diffuse reflection helps in seeing the objects and is responsible for the ability to see most illuminated surfaces from any position.
Types of Reflection
In both regular and irregular reflections, the laws of reflection are followed.
Law of Reflection Formula:
The law of reflection formula is given as:
θi = θr
Where,
θi is the angle of incidence
θr is the angle of reflection
Laws of reflection
What is Angle of Reflection?
The angle of reflection Θr of a ray is the angle measured from the reflected ray to the normal surface.
Calculation of Angle of Incidence and Angle of Reflection
The angle of incidence and the angle of reflection are calculated by drawing a normal line that is perpendicular to the reflecting surface.
Examples of Laws of Reflection
Q1: A ray of light is incident towards a plane mirror at an angle of 30° with the mirror surface. What will be the angle of reflection?
Ans:
Since the angle of incidence is measured between the incident ray and the normal, so, here the angle of incidence is not 60°
According to the Law of Reflection,
θi = θr
Hence,
Angle of Reflection = 60°
Q2: A light ray strikes a reflective plane surface at an angle of 54° with the surface.
(i) Calculate the angle of incidence.
(ii) Calculate the angle of reflection.
(iii) Calculate the angle made by the reflected ray and the surface.
(iv) Calculate the angle made by the incident and reflected rays.
Ans:
(i) Angle of incidence, θi = 90° – 54°=36°
(ii) Angle of Reflection, θr = 36° (As per Law of Reflection)
(iii) Angle made by the reflected ray and the surface,
q=90° – r = 90° – 36° = 54°
(iv) Angle made by the incident and reflected rays,
θi = θr =36° + 36° = 72°
Q3:
Laws Of Reflection Questions
Find angle α made by the system of the two mirrors shown in the figure below so that the incident ray at A and the reflected ray at B are parallel.
Ans:
Laws Of Reflection Questions
We first complete the given diagram with the angles of incidence and reflection as shown below and also labelling the incident and reflected rays.
For the incident ray at A and the reflected ray at B to be parallel, angles i + r and i’ + r’ have to be supplementary. (geometry: parallel lines cut by a transversal).
Hence,
i + r + i’+ r’ = 180 °
by law of reflection : r = i and r’ = i’
Substitute to obtain
i + i + i’ + i’ = 180 °
i + i’ = 90
In triangle AOB, we have
α + (90 – r) + (90 – i’) = 180 °
α = r + i’ = i + i’ = 90 °
If α = 90 °, the incident ray at A and the reflected ray at B are parallel.