Human Eye and Colourful World — Science STD 10 — Question

When light rays enter the eye, most of the refraction occurs at the:

1. Crystalline lens.
2. Outer surface of the cornea.
3. Iris.
4. Pupil.

Electric heaters used for cooking have the filament or the heating coil on a plate made up of clay because

An illuminated object is placed at a distance of 20cm from a converging lens of focal length 15cm. The image obtained on the screen is:

1. Upright and magnified.
2. Inverted and magnified.
3. Inverted and diminished.
4. Upright and diminished.

In the arrangement shown in Figure there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted. Then the key is inserted and later removed. Then,

A student traces the path of a ray of light through a rectangular glass slab for four different angles of incidence. He very cautiously measures the angle f, angle r and the angle e. On analysing his measurements, he is likely to draw the following conclusion:

After testing the eyes of a child, the optician has prescribed the following lenses for his spectacles:
Left eye: +2.00D
Right eye: +2.25D
The child is suffering from the defect of vision called:

1. Short-sightedness.
2. Long-sightedness.
3. Cataract.
4. Presbyopia.

A student obtained a sharp inverted image of a distant tree on a screen placed in front of the concave mirror. He then removed the screen and tried to look into the mirror. He would now see

A hollow glass prism gives:

Which part of eye is responsible for its characteristic colour:

Choose the correct option.
A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each,