Electricity — Science STD 10 — Question

Magnification produced by a convex mirror is always:

An object is place placed at a distance of half the focal length of a convex lens. The Image will be:

At noon the sun appears white as:

A soft iron bar is inserted inside a current-carrying solenoid. The magnetic field inside the solenoid:

If the direction of electric current in a solenoid when viewed from a particular end is anticlockwise, then this end of solenoid will be:

The atmospheric refraction of light causes the twinkling of:

1. Planets only.
2. Stars only.
3. Planets and stars.
4. Stars and satellites.

A burning candle whose flame is 1.5cm tall is placed at a certain distance in front of a convex lens. An image of candle flame is received on a white screen kept behind the lens. The image of flame also measures 1.5cm. If f is the focal length of convex lens, the candle is placed:

1. At f.
2. Between f and 2f.
3. At 2f.
4. Beyond 2f.

A full length image of a distant tall building can definitely be seen by using:

A plotting compass is placed near the south pole of a bar magnet. The pointer of plotting compass will:

1. Point away form the south pole.
2. Point parallel to the south pole.
3. Point towards the south pole.
4. Point at right angles to the south pole.

Which of the following is used as a moderator in the reactor of a nuclear power station?

1. Liquid sodium.
2. Boron.
3. Graphite.
4. Carbon dioxide.