Metals.

Q2. What are metals?

or

Define metals?
Ans. Metals are malleable, ductile and good conductor of heat and electricity. They possess high melting point and boiling point. Example: Copper, Sodium, Aluminum, Potassium etc.
On the basis of chemical reaction, metals are defined as follows:
Metals are those elements which form positive ions( cations) by losing electrons. Because of this property metals are also known as electropositive elements.

Ray Of Light Passing Through The Center Of Curvature.

Q36. Explain why a ray of light passing through the center of curvature of a concave mirror gets reflected along the same path.
Ans. This is because the angle of incidence is 0o, that is the rays passing through the center of curvature is incident it normally to the mirror.

Type of Mirrors used.

Q32. Name the type of mirrors used in the following situations:

  1. Headlight of a car,
  2. Side view mirror of a vehicle,
  3. Solar furnace.

Support your answer with reason.
Ans.

  1. Headlight of a car: Concave Mirrors are used in vehicles headlights to get powerful beams of light. This is because when a lighted bulb is placed at the focus of a concave reflector, then it produces a powerful beam of parallel light rays. This helps us to see things up to a considerable distance in the darkness of night.
  2. Side view mirror of a vehicle: It is used as rear view Mirror in vehicles to see the traffic at the rare side. (Convex Mirrors are preferred because there always give an erect even though diminished image, they have a wider field of view as they are curved outwards).
  3. Solar furnace: Large Concave Mirrors are used in the Solar furnace to concentrate sun light to produce maximum heat. Solar furnace is placed at the focus of a large concave reflector. It focuses the sun’s heat rays on the furnace due to which the Solar furnace gets very hot.

The magnification produced by a plane mirror is +1.

Q31. The magnification produced by a plane mirror is +1. What does it mean?
Ans. The value 1 shows that, size of the image formed by the plane mirror is equal to the object.

The positive sign(+) in the value shows that the image formed by the plane mirror is virtual and erect.