 ## Question Bank on light for Class 10th

### What is light?

Light is a form of energy that enables us to see objects. It is an electromagnetic wave that travels at a speed of 299,792,458 meters per second in a vacuum.

### What is the source of light?

The source of light can be natural or artificial. The sun is a natural source of light, and light bulbs are artificial sources of light.

### How does light travel?

Light travels in a straight line until it encounters an obstacle or is refracted by a medium.

### What is reflection of light?

Reflection of light is the bouncing back of light when it strikes a surface. It follows the law of reflection, which states that the angle of incidence is equal to the angle of reflection.

### What is refraction of light?

Refraction of light is the bending of light when it passes from one medium to another. It occurs because the speed of light changes when it passes through different mediums.

### What is the difference between reflection and refraction of light?

Reflection of light involves the bouncing back of light when it strikes a surface, whereas refraction of light involves the bending of light when it passes from one medium to another.

### What is the spectrum of light?

The spectrum of light is the range of colors that make up white light. These colors are red, orange, yellow, green, blue, indigo, and violet.

### What is dispersion of light?

Dispersion of light is the separation of light into its different colors when it passes through a prism. It occurs because each color of light has a different wavelength and is bent at a slightly different angle when it passes through the prism.

### What is the speed of light?

The speed of light is approximately 299,792,458 meters per second in a vacuum.

### What is the unit of measurement for the speed of light?

The unit of measurement for the speed of light is meters per second (m/s).

### What is the law of reflection?

The law of reflection states that the angle of incidence is equal to the angle of reflection. This means that the angle at which a ray of light strikes a surface is the same as the angle at which it bounces off the surface.

### What is a concave mirror?

A concave mirror is a curved mirror where the surface is curved inward. It can converge light rays and form real or virtual images depending on the distance of the object from the mirror.

### What is a convex mirror?

A convex mirror is a curved mirror where the surface is curved outward. It always forms a virtual image, and the image appears smaller than the object.

### What is the focal length of a lens?

The focal length of a lens is the distance between the lens and its focal point. It determines the amount of convergence or divergence of light rays passing through the lens.

### What is the difference between a convex and concave lens?

A convex lens is thicker at the center than at the edges and converges light rays. On the other hand, a concave lens is thinner at the center than at the edges and diverges light rays.

### What is the relationship between the object distance, image distance, and focal length of a lens?

The object distance, image distance, and focal length of a lens are related by the equation: 1/f = 1/d₀ + 1/dᵢ, where f is the focal length, d₀ is the object distance, and dᵢ is the image distance.

### What is total internal reflection?

Total internal reflection is the complete reflection of light when it travels from a denser medium to a less dense medium at an angle greater than the critical angle. It is responsible for the reflective properties of optical fibers.

### What is the difference between transparent, translucent, and opaque objects?

Transparent objects allow all light to pass through and can be seen clearly. Translucent objects allow some light to pass through but scatter it in all directions, making the object appear blurry. Opaque objects do not allow any light to pass through and cannot be seen through.

### What is the difference between luminescence and incandescence?

Luminescence is the emission of light from a material without being heated, while incandescence is the emission of light from a material when heated to a high temperature.

### What is the difference between a regular and irregular reflection?

Regular reflection occurs when light is reflected from a smooth surface, and the reflected rays remain parallel to each other. In contrast, irregular reflection occurs when light is reflected from a rough surface, and the reflected rays scatter in all directions.

### What is the difference between a converging and diverging lens?

A converging lens is thicker at the center than at the edges and converges light rays. On the other hand, a diverging lens is thinner at the center than at the edges and diverges light rays.

### What is the difference between a plane, concave and convex mirror?

A plane mirror is a flat mirror that produces a virtual image. A concave mirror is a curved mirror where the surface is curved inward and can form real or virtual images. A convex mirror is a curved mirror where the surface is curved outward and always forms a virtual image.

### What is the relationship between frequency and wavelength of light?

The frequency and wavelength of light are inversely proportional to each other. As the frequency of light increases, its wavelength decreases, and vice versa.

### What is the difference between a photovoltaic cell and a photoelectric cell?

A photovoltaic cell is a device that converts light energy into electrical energy by the photovoltaic effect. A photoelectric cell is a device that emits electrons when exposed to light and is used in photocells and photomultipliers.

### What is the difference between the color of an object and the color of light it reflects?

The color of an object is the result of the wavelengths of light that are absorbed by the object's surface. The color of light that an object appears to be is the color of the light that is reflected by the object.

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