- Which instrument is used to see heavenly bodies? Telescope.
- What will the red ribbon look like in green light? Black
- How long does it take for sunlight to reach the surface of the earth? 8 minutes 20 secs
- Power of a lens is measured in which of the following? Diopters
- What is the light year? Measure distance
- Primary colors are – Red, Green, Blue
- .When the sunlight comes out of the prism, which color deviates the most? Violet
- For what reason does the color of the sky appear blue? Scattering of light.
- .How many colors are there in sunlight? 7
- The sky appears blue because Scattering of light by air molecules
- With what the intensity of light measured ? Photometer
- Lens used foresightedness? Convex
- Which lens is used in a simple microscope? convex lens
- the main source of heat is the sun
- Name the defect of eye in which a person cannot simultaneously focus on both horizontal and vertical lines? Astigmatism
- Astigmatism is corrected with cylindrical lens
- which of the following is used as a magnifying glass is? convex lens
- How long does it take for the rays of sun to reach Earth? 500 seconds or 8 minutes and 19 seconds.
- convex mirror is used for rear view in cars Type of image formed in a concave mirror? real and virtual
- The ratio of size of the image to the size of the object is called magnification
- Electrical energy is converted into what inside a photocell? light energy
- light is electromagnetic radiation
- Twinkling of star is due to refraction of light
- .Sun is the source of natural light on earth
- What causes star to shine own light. Sun
- Light is an energy.
- The device which converts solar energy into electrical energy is solar cel
- Which lens is used in simple microscope? convex lens
- light is electromagnetic radiation
- twinkling of star is due to refraction of ligh
- Electrical energy is converted into what inside a photocell? light energy
- In which order are the colours in rainbow? VIBGYOR
- If the image of an object is small and real then used lens will be convex
- out of all nuclear radiation the most damaging radiation is Gamma
- An ellipse of Sun takes place when the moon passes between the sun and the earth
- which is not primary colour? yellow
- Light is in the form of an electromagnetic wave
- The visible light has wavelengths of 400–700 nm.
- The primary source of light is sun.
- Optics is a branch of physics that deals with the study of light.
- Light speed is 3 x 108 m/s
- Light is a transverse wave.
- The angle of incidence is equal to the angle of reflection.
- The incident ray, the reflected ray and the normal to the mirror at the point of incidence all lie in the same plane.
- A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the centre of the sphere, is called a concave mirror.
- Bending of light rays from its path when it travels from one transparent medium to another medium is called refraction of light.
- Due to refraction from Earth’s atmosphere, the stars appear to twinkle.
- A coin appears at lesser depth in water.
- Sparkling of diamond, mirage and looming, shining of the air bubble in water and optical Fibre are examples of total internal reflection.
- The image formed by a concave mirror is generally real and inverted
- The image formed by a convex mirror is always virtual and erect.
- The midpoint of a spherical mirror is called a pole.
- Light after reflection it meets at a point on the principal axis, called focus (F)
- Focal length is the distance between focus and pole. f= R/2
- Light is incident on a glass prism, it disperses into its seven colour components in the following sequence VIBGYOR, and this is known as the dispersion of white light.
- Rainbow is caused by dispersion of sunlight
- The Sun is visible to us about 2 minutes before the actual sunrise because of refraction.
- Red has the lowest frequency and the high wavelength.
- Isaac Newton discovered that white light consists of seven colours
- Sky is blue is because of scattering of light
- Sunlight becomes visible when it passes through dust particles in a room due to Tyndall effect.
- If our Earth did not have an atmosphere, the sky would be black like outer space.
- Convex lens is called as a converging lens
- concave lens is called as a diverging lens
- right appears to be left and left appears to be right in mirror which is called as lateral inversion
- Photoelectric effect was given by Einstein
- Concave mirror is used in searchlights
- Concave mirror is used in reflecting telescopes.
- Convex mirror is used in rear view mirrors of vehicle
- Person suffering from myopia uses concave lens
- Person suffering from hypermetropia uses convex lens
- The line passing through midpoint of lens and principal axis is called Pole
- Convex mirror is used in street light lamps.
- Concave mirror is used in search lights.