Electricity — Science STD 10 — Question

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:

The magnification produced by a spherical lens and a spherical mirror is +2.0.

In a convex spherical mirror, reflection of light takes place at:

1. A flat surface.
2. A bent-in surface.
3. A bulging-our surface.
4. An uneven surface.

Suppose you have focused on a screen the image of candle flame placed at the farthest end of the laboratory table using a convex lens. If your teacher suggests you to focus the parallel rays of the sun, reaching your laboratory table, on the same screen, what you are expected to do is to move the:

Which of the following is the most likely temperature of the filament of an electric light bulb when it is working on the normal 220V supply line?

1. 500°C
2. 1500°C
3. 2500°C
4. 4500°C

You are given water mustard oil, glycerine and kerosene. In which of these media a ray of light incident obliquely at same angle would bend the most?

Which of the following can make a parallel beam of light from a bulb falls on it?

1. Concave mirror as well as concave lens.
2. Convex mirror as well as concave lens.
3. Concave mirror as well as convex lens.
4. Concave mirror as well as convex lens.

The colour of white light which suffers the maximum bending (or maximum refraction) on passing through a glass prism is:

1. Yellow.
2. Orange.
3. Red.
4. Violet.

An examples of a renewable source of energy is:

1. Petrol.
2. Natural gas.
3. Biogas.
4. Kerosene.

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: