Human Eye and Colourful World — Science STD 10 — Question

The north-south polarities of an electromagnet can be found easily by using:

A student obtained a sharp image of a candle flame placed at the distant end of the laboratory table on a screen using a concave mirror to determine its focal length. The teacher suggested him to focus a distant building about 1 km far from the laboratory, for getting more correct value of the focal length. In order to focus the distant building on the same screen the student should slightly move the:

The control rods used in the reactor of a nuclear power plant are made of:

1. Steel.
2. Graphite.
3. Uranium.
4. Boron.

All appliances in a domestic electric circuit are connected in parallel so that:

A parallel beam of light falling on the eye gets focused on the retina because of refractions at:

One coulomb charge is equivalent to the charge contained in:

1. 2.6 × 10¹⁹ electrons.
2. 6.2 × 10¹⁹ electrons.
3. 2.65 × 10¹⁸ electrons.
4. 6.25 × 10¹⁸ electrons.

In the statement of Fleming's left hand rule, magnetic field is represented by:

Shape of eye ball is:

The image formed on the retina of the human eye is:

Magnification produced by a rear view mirror fitted in vehicles: