Human Eye and Colourful World — Science STD 10 — Question

A student obtained a sharp image of a burning candle, placed at the farther end of a laboratory table, on a screen using a concave mirror. For getting better value of focal length of the mirror, the subject teacher suggested him for focusing a well illuminated distant object. What should the student do?

A student is using a convex lens of focal length 10 cm to study the image formation by a convex lens for the various positions of the object. In one of his observations, he may observe that when the object is placed at a distance of 20 cm from the lens, its image is formed at (select the correct option):

The animals of prey have:

The coloured light having the maximum speed in glass prism is:

1. Blue.
2. Green.
3. Violet.
4. Yellow.

The strength of magnetic field inside a long current carrying straight solenoid is:

If the solar constant is 1.4kW/ m² then solar energy recived by 1m²area in one hour is:

1. 5040J.
2. 504.0kJ.
3. 5040kJ.
4. 5.04kJ.

Which of the following statement is correct?

1. A person with myopia can see distant objects clearly.
2. A person with hypermetropia can see nearby objects clearly.
3. A person with myopia can see nearby objects clearly.
4. A person with hypermetropia cannot see distant objects clearly.

A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.

________are substances which do not allow electricity to pass through them:

The magnification produced by a spherical lens and a spherical mirror is +2.0.

1. The lens and mirror are both concave.
2. The lens and mirror are both convex.
3. The lens is convex but the mirror is concave.
4. The lens is concave but the mirror is convex.