Optics
Light is a form of electromagnetic radiation that is visible to the human eye. It is a type of energy that travels in waves and can be described by its wavelength and frequency. Visible light is just a small part of the electromagnetic spectrum, which includes radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays, and gamma rays.
Here are some key aspects of light:
- Electromagnetic Radiation: Light is a form of electromagnetic radiation, meaning it is composed of oscillating electric and magnetic fields traveling through space.
- Wave-Particle Duality: Light exhibits properties of both waves and particles. As a wave, it has characteristics like wavelength and frequency. As a particle, it is composed of photons, which are discrete packets of energy.
- Visible Spectrum: The portion of the electromagnetic spectrum that humans can see is called the visible spectrum, which ranges from red (longer wavelengths) to violet (shorter wavelengths).
- Speed of Light: Light travels at a constant speed in a vacuum, approximately 299,792,458 meters per second (often denoted as c). This is the fastest speed at which energy or information can travel.
- Interaction with Matter: Light can be reflected, refracted (bent), absorbed, or transmitted when it interacts with matter. These interactions give rise to phenomena like color, shadows, and optical illusions.
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Here's the solution to the problem:
Given:
- Object height, h = 5 cm
- Object distance, u = -15 cm (negative as per sign convention)
- Focal length, f = -10 cm (negative for concave mirror)
To find:
- Image distance, v
- Image height, h'
Solution:
We can use the mirror formula to find the image distance:
1/f = 1/v + 1/u
Substituting the given values:
1/(-10) = 1/v + 1/(-15)
-1/10 = 1/v - 1/15
1/v = -1/10 + 1/15
1/v = (-3 + 2)/30
1/v = -1/30
v = -30 cm
The screen should be placed 30 cm in front of the mirror to obtain a focused image.
Now, we can use the magnification formula to find the height of the image:
Magnification, m = h'/h = -v/u
Substituting the known values:
h'/5 = -(-30)/(-15)
h'/5 = 30/-15
h'/5 = -2
h' = -10 cm
The height of the image is 10 cm. The negative sign indicates that the image is inverted.
Answer:
- The screen should be placed 30 cm away from the mirror.
- The height of the image is 10 cm. The image is inverted.
Note: These calculations follow the sign conventions used in optics.
Another name for a convex mirror is a diverging mirror.
This is because convex mirrors always reflect light outwards, diverging the light rays.
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A convex mirror is also called a diverging mirror.
This is because when parallel rays of light strike the surface, the reflected rays diverge or spread out from each other.
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A convex lens is called a converging lens because of its shape and how it affects light rays passing through it.
- Shape: A convex lens is thicker in the middle and thinner at the edges.
- Refraction: When parallel light rays pass through a convex lens, they are refracted (bent) towards the normal (an imaginary line perpendicular to the surface of the lens). Due to the lens's curved shape, the light rays are bent inwards.
- Convergence: This bending of light rays causes them to converge or meet at a single point on the opposite side of the lens. This point is called the focal point.
Therefore, because a convex lens causes parallel light rays to come together or converge at a point, it is aptly named a converging lens.