The Human Eyes And The Colourful World — Science STD 10 — Question

A strong bar magnet is placed vertically above a horizontal wooden board. The magnetic lines of force will be:

1. Only in horizontal plane around the magnet.
2. Only in vertical plane around the magnet.
3. In horizontal as well as in vertical planes around the magnet.
4. In all the planes around the magnet.

Change in focal length of an eye-lens to focus the image of the object at varying distances is done by the action of:

An electric generator converts:

1. Electrical energy into mechanical energy.
2. Mechanical energy into heat energy.
3. Electrical energy into chemical energy.
4. Mechanical energy into electrical energy.

A person cannot see distinctly objects kept beyond 2m. This defect can be corrected by using a lens of power:

1. +0.5D
2. -0.5D
3. +0.2D
4. -0.2D

Refraction of light by the earth’s atmosphere due to variation in air density is called:

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:

The image formed by a spherical mirror is virtual. The mirror will be:

1. Concave.
2. Convex.
3. Either concave or convex.
4. Metallic.

A current flows in a wire running between the S and N poles of a magnet lying horizontally as shown in Figure below:

The force on the wire due to the magnet is directed:

1. Fron N to S.
2. From S to N.
3. Vertically downwards.
4. Vertically upwards.

If the index finger points towards the north and the middle finger towards the east, when using Flemings left-hand rule, what will be the direction of motion or that of the force acting on the conductor?

n normal use, a current of 3.5A flows through a hair dryer. Choose a suitable fuse from the following: