Q5 of 30 Page 1

When we enter a dark room coming from outside, immediately the things inside the room do not appear clear to our eyes. This is because

The human retina relies on two types of photoreceptors for this phenomenon called dark adaptation. The cone cells, respond to light even high levels of illumination.

Rods are photoreceptors for night vision and work slowly when a person is entering from a brightly lit room to dimly lit room.


In the dark, the pupil dilates to let more light in.


Both these cells slowly increase their sensitivity to light in a dim environment. Cones adapt faster than the rod cells.


OR


ii) Refraction


Refraction is the phenomenon responsible for image formation by the eye. The rays usually reach the eyes after reflecting off the surfaces. Refractive errors that occur are imperfections which prevent the proper working of the eye and can be rectified using proper lenses or sometimes by surgical methods.

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3

Answer question numbers 3(a) - 3(d) on the basis of your understanding of the following paragraph and the related studied concepts.

Renewable energy sources such as wind energy are vital for the Indian economy, not only from the point of view of supply, but also from the perspective of environmental and social benefits.


India is the world’s fifth largest wind-power producer and the largest


windmill facilities in India are installed in Tamil Nadu. Muppandal is a small village of Tamil Nadu and one of the most important sites of wind-farm in the state.



It uses wind from the Arabian Sea to produce renewable energy. The suitability of Muppandal as a site for wind farms stems from its geographical location as it has access to the seasonal monsoon winds.


The electrical generators used on wind turbines in sites like Muppandal, produce an output AC of 240 V and a frequency of 50 Hz even when the wind speed is fluctuating. A transformer may be required to increase or decrease the voltage so it is compatible with


the end usage, distribution or transmission voltage, depending on the type of interconnection.


(a) State the principle behind electric generator.


(b) The output frequency of wind turbine is 50 Hz. What is meant by this statement?


(c) Why do you think Muppandal is at an advantageous position for this project?


(d) Based on the data represented in the graph below, which of the two cities A or B would be an ideal location for establishing a wind-farm and why?



 4

Question numbers 4(a) - 4(d) are based on the two tables given below. Study these tables related to blood sugar levels and answer the questions that follow.


(a) Refer to Table B showing the blood report of the levels of glucose of patients X and Y. Infer the disease which can be diagnosed from the given data.


(b) Identify the hormone whose level in the blood is responsible for the above disease.


(c) Which one of the following diets would you recommended to the affected patient?


i) High sugar and low fat diet.


ii) Low sugar and high protein diet.


iii) High Fat and low fiber diet.


iv) Low sugar and high fiber diet.


(d) Refer to the Table A and suggest the value of the mean blood glucose level beyond which doctor’s advice is necessary:


i) 180 mg/dL


ii) 115 mg/dL


iii) 50 mg/dL


iv) 80 mg/dL


 6

When a 4V battery is connected across an unknown resistor there is a current of 100 mA .in the circuit. The value of the resistance of the resister is:

 7

Unit of electric power may also be expressed as: