Free Light 01 Practice Test - 7th grade
Question 1
Which amongst the following is not a characteristic of an image formed by a plane mirror?
SOLUTION
Solution : D
Plane mirrors always produce an image that is virtual, erect, laterally inverted and of the same size as the object. Also, the image distance from the mirror is always equal to the object distance from the mirror.
Question 2
Which type of mirror is used as a rear-view mirror in cars?
SOLUTION
Solution : B
Convex mirrors are commonly used as rear-view mirrors in vehicles because they give erect, virtual and diminished images of distant objects with a wider field of view. Thus, convex mirrors enable the driver to view a much larger area than would be possible with a plane mirror.
Question 3
What type of mirror is used in the headlights of a car?
Plane
Convex
Concave
Plano concave
SOLUTION
Solution : C
Concave mirrors are used in the headlights of a car.
When a bulb is placed at the focus of a concave reflector, the reflector collects the light rays and direct them into a powerful beam (in form of parallel rays) after reflection. Such beam can reach a large distance in dark and enable vision up to greater distances.
Question 4
Which type of spherical mirror does the inner surface and the outer surface of a polished spoon act as?
SOLUTION
Solution : A
A spherical mirror is a mirror with a curved reflecting surface. The surface may be either convex (bulging outward) or concave (bulging inward). The inner surface of a spoon acts as a concave mirror and the outer surface of the spoon acts as a convex mirror.
Question 5
A virtual image can be formed on a screen.
True
False
SOLUTION
Solution : B
A virtual image cannot be formed on a screen. Only real images are formed on a screen.
Question 6
Plane mirror is also known as convergent mirror.
True
False
SOLUTION
Solution : B
The radius of curvature of a plane mirror is infinite. Therefore it is neither a convergent nor a divergent mirror.
Convex mirror is a divergent mirror and concave mirror is a convergent mirror.
A concave mirror is called a converging mirror because it brings incoming parallel rays together. It causes these rays to converge.
Question 7
A convex lens always forms a virtual image.
True
False
SOLUTION
Solution : B
The image formed by the convex lens can be real or virtual depending on the distance between the object and the lens. Real images only occur for objects which are placed outside and far from the convex lens. Virtual images are formed by placing an object between focus and pole of the mirror.
Question 8
A magnified virtual image can be produced by a ______
SOLUTION
Solution : B
When the object is kept in between focus and the pole, a concave mirror forms an enlarged, virtual and erect image. A convex mirror always form diminished virtual image. A plane mirror always forms a virtual and erect image without any magnification.
Question 9
Which among the following disc's appear white when it is roataing.
SOLUTION
Solution : D
Newton's disc has different segments painted in different colours. They are painted in the order of Violet, Indigo, Blue, Green, Yellow, Orange and Red. When the disc is rotating, all the colours appear to be white. Isaac Newton used this disc to demonstrate that white light is a combination of the seven different colours.
Question 10
Match the following:
| (A) Plane mirror | (1) Always virtual, erect and dimnished image |
| (B) Convex mirror | (2) Image is erect and of the same size as the object |
| (C) Convex lens | (3) Used by dentists to see enlarged images of teeth |
| (D) Concave mirror | (4) Used in microscope. |
SOLUTION
Solution : D
A plane mirror forms a virtual and erect image. The size of an image is the same as the size of the object.
A convex mirror always forms a virtual, erect and diminished image.
A convex lens can form enlarged images and thus are used in magnifying glass and microscope.
Dentists use a concave mirror to see an enlarged image of the teeth. If an object is placed close to a concave mirror it a forms an erect and enlarged image of the object.