Q1: Name the essential part of human eye.
Answer: Pupil, Retina, Optic nerves, Iris, Cornea, Eye lens
Q2: Name the liquid present behind the cornea in human eye.
Answer: Aqueous Humour is the liquid present behind the cornea in human eye.
Q3: Which part of human eye controls the amount of light entering the eye?
Answer: Pupil
Q4: What is eye lens made up of?
Answer: Eye lens are made up of transparent and flexible jelly like substance.
Q5: What is the fuction of optic nerve?
Answer: The function of optic nerve is to send the information of image formed at retina to the brain.
Q6: Which liquid present between eye lens and retina?
Answer: Vitreous humour
Q7: Why is blind spot so called?
Answer: Blind spot is so called because image formed at ths point is not sent to brain.
Q8: What is meant by far point?
Answer: Far point simply means that, the farthest distance upto which eye can see the object distinctly.
Q9: What is meant by near point?
Answer: Near point simply means that, the nearest distance upto which eye can see the object properly.
Q10: Why can you not see an object clearly if it is placed very close to your eye?
Answer: We can't see an object which is placed very close to our eye because short distance of distinct vision is 25 cm.
Q11: When you enter from a bright sunshine into a dark room, you are not able to see clearly for sometime, why?
Answer: We are not able to see anything when we come from bright sunshine into a dark room because the size of the pupil get bigger as we come from bright light to dim light.
Q12: What is presbyopia?
Answer: Presbyopia is a kind of defect of vision which happens due to ageing which happens due to decreses in flexibility of eye lens and weakening of ciliary muscle.
Q13: Which kind of lens is use to treat a person suffering from myopia?
Answer: A concane or diverging lens is used to treat a person suffering from myopia.
Q14: Name the part of the human eye that helps in changing the focal length of eye lens.
Answer: Ciliary muscle is responsible for adjusting the focal lenght of eye lens.
Q15: What is the value of short distance for distinct vision for normal eye?
Answer: 25 cm
Q16: What is the role of pupil in human eye?
Answer: Pupil helps in regulating and controling light entering inside the eyes with the help of iris.
Q17: A person is advised to wear spectacles with concave lenses. What type of defect of the vision is he sufferening from?
Answer: Myopia
Q18: Name the part present in eye which is responcible for the power of accommodation of the eye.
Answer: Ciliary muscle
Q19: Name the condition resulting due to the eye lens becoming cloudy.
Answer: Cataract
Q20: A person suffereing from an eye defect using lenses of power -1D. Name the defect he is suffereing from and the nature of lens used.
Answer: He is using concave lens and he is suffereing from myopia.
Q21: Define the power of accommodation?
Answer: Power of accommodation means the power of the eye lens to focus on an objects near or far from the retina by adjusting its focal length with the help of ciliary muscle.
Q22: Which part of the human eye provides most of the refraction for the light rays entering the eye?
Answer: Cornea and Aqueous humour
Q23: What happens to the image distance in the eye when we increase the distance of an object from the eye?
Answer: Image of object always form on retina, it doesn't depend upon distance of object because eye has a power of accommondation to adjust focal lenght of eye lens.
Q24: What happens to the pupil of the eye when the light is very bright?
Answer: The size of the pupil become smaller when the light is very bright.
Q25: Which part of the human eye conveys the electrical signals generated by the light sensitive cells of the retina to the brain?
Answer: Optical nerves
Q26: Name one defect of vision which cannot be corrected by any type of spectacle lens?
Answer: Cataract
Q27: What is the nature of the image formed on the retina of the eye?
Answer: Real and Inverted
Q28: What type of lens is used for correcting hypermetropia?
Answer: Convex lens
Q29: Write in one word or at the most in one sentence about the following:
(i) Mirrors used by dentists to examine teeth.
(ii) The smallest distance, at which the eye can see objects clearly without strain.
Answer: (i) Concave mirror
(ii) Near point or 25 cm.
Q30: The ciliary muscles of a normal eye are in their
(i) most relaxed
(ii) most contracted state.
In which of the two cases is the focal length of the eye-lens more?
Answer: In most relaxed state.
