Reflection of Light — Science STD 10 — Question

In order to determine focal length of a concave mirror by obtaining the image of distant object on screen, you need to measure the distance between:

A 1.25kW heater works on a 220 B mains supply. What current rating would a suitable fuse have?

1. 2A
2. 5A
3. 10A
4. 13A

In a filament type light bulb, most of the electric power consumed appears as:

The clear sky appears blue because:

1. Blue light gets absorbed in the atmosphere.
2. Ultraviolet radiations are absorbed in the atmosphere.
3. Violet and blue lights get scattered more than lights of all other colours by the atmosphere.
4. Light of all other colours is scattered more than the violet and blue colour lights by the atmosphere.

The atmospheric refraction of light causes the twinkling of:

The elements of electrical heating devices are usually made of:

The steps involved in observing a slide under a microscope are given below. They may not be in proper sequence.

1. 
   Focus the object under high power of the microscope.
2. 
   Place the slide on the stage of the microscope.
3. 
   Arrange the mirror to reflect maximum light to the slide.
4. 
   Focus the object under low power of the microscope.

The proper sequence of steps is:

A convex lens has a focal length of 10cm. At which of the following position should an object be placed so that this convex lens may act as a magnifying glass?

1. 15cm
2. 7cm
3. 20cm
4. 25cm

In the case of hypermetropia:

When a bar magnet is broken into two pieces: