Tuesday, 23 February 2016

CLASS VIII REVISION WORKSHEET
LESSON-LIGHT
Give one word for the following : 1. The invisible energy which causes in use the sensation of vision. 2. The ray of light which travels towards a mirror.
 3. A line which is drawn at right angles to the mirror surface at the point of incidence.
 4. Name one type of mirror which always form virtual image.
 5. What type of image is formed on the cinema screen ?
 6. Which cells on the retina respond to the intensity of light.
 7. The part of the eye which preserves its shape and protects it from external injuries.
 8. The phenomenon due to which we can judge depth.
9. The most sensitive part of the retina.
Fill in the blanks : 1. The point at which the incident ray falls on the mirror is called ___________________
 2. If a ray of light is incident on a plane mirror at an angle of 300 , its angle of reflection is _______________.
 3. If a ray of light is incident normally on a mirror, i = __________ and r = ________________ 4. The image of our face in a plane mirror is an example of ___________ image.
5. The distance of the image behind the plane mirror is _________ to the distance of the object in front of it.
 6. The principle of ___________is made use of in motion picture projection in cinematography.
 7. The presence of __________________ cells on the retina helps us to see in dim light
. 8. The coned shaped cells of our retina respond to _____________
 9. Due to the absence or insufficient number of ____________ cells a person becomes colour blind. 10. Owls and bats are able to see at night due to the presence of ______________ cells in their retina. 11. The thin, saline liquid that fills the anterior part of the eye is _________.
12. ___________ is the jelly like fluid found in the posterior part of the eye.
 13. In a spectrum formed by a prism ______ colour deviates the least and ____________ colour deviates the most.
 Multiple choice questions :
 1. The scientist who discovered that white light is composed of 7 colours
. [ Louis Braille, Dalton, Issac Newton]
 2. _____________________ can be donated after death, to enable a blind person see. [ optic nerve, cornea, iris]
 3. The part of the retina which is insensitive to light. [ cornea, yellow spot, blind spot]

4. Focal length of the eye lens can be adjusted by the action of [ choroid, ciliary muscles, optic nerve] 5. Formation of multiple images in the eyes is avoided by the action of [iris, pupil, choroid]
 6. The colour of a person‟s eye is determined by his [pupil, iris, retina]
 7. Electric pulses from retina to brain is conveyed through [ciliary muscles, optic nerves, pupil]

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