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 carsType 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