Name the lens which can concentrate sun's rays to a point and burn a hole in a piece of paper.

Name some ores which can be concentrated by magnetic separation method.

Which of the following can be drawn on a piece of paper ?

A child while playing with his father's spectacles, burnt a hole in a piece of tissue paper by focussing the image of the sun on the paper. (a) Name the defect of vision his father is suffering from. (b) List two causes of the defect. ( c) Draw a ray diagram to show this defect may be corrected using a suitable lens.

Name the defect of vision which can ne corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect.

Which one of the following cations will give a green coloured ash when a piece of filter paper dipped in a solution containing its salt and Co(NO_(3))_(2) is burned?

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of carbon paper for some time, a hole is burnt in the carbon paper. (a) What is the nature of spherical mirror ? (b) Why is a hole brnt in the carbon paper ? ( c) At which point of the spherical mirror the carbon paper is placed ? (d) What name is given to the distance between spherical mirror and carbon paper ? ( e) What is the advantage of using a carbon paper rather then a white paper ?

Name the defect of vision which can be corrected by a diverging lens. Show clearly by a ray diagram how the lens corrects the defect.