Light Energy Test - 5

Ray optics is valid when characteristic dimension are much larger than wavelength of light . The size of obstacle must be much larger than the wavelength of light. If wavelength is comparable to the size of object, then diffraction could happen, but it cannot be explained using ray optics, it will require wave theory of light.

Accordingto the question the correct option will be ‘D’ because when light rays arepassed through a prism, the phenomenon that happens is known as the dispersion oflight. The splitting of white light into its constituent colors is known asdispersion.

According to the question the correct option will be ‘C’ because Concave mirrors are usedin the headlights of a car.
When a lighted bulb is placed at the focus of a concave reflector, the reflector collects the light rays and directs them into a powerful beam (in form ofparallel rays) after reflection. Such beam can reach a large distance in darkand enable vision up to greater distances. 

According to the question thecorrect option will be ‘C’ because Concave mirrors are used in torches used athomes or by dentists.

In a torch, the bulb is placed at the focalpoint of the concave mirror so the light from the bulb is reflected as aparallel beam. This helps users to specifically see the desired object.

According to the question the correct option will be ‘A’ because Image formed by a planemirror is erect and always of the same size as the object. The image formed bya convex mirror is upright but reduced in size whereas in a concave mirror thesize of image is not fixed.

According to the question the correct option will be ‘D’ because Newton's disc hasdifferent segments painted in different colors. They are painted in the order ofViolet, Indigo, Blue, Green, Yellow, Orange and Red. When the disc is rotating,all the colors appear to be white. Isaac Newton used this disc to demonstrate that white light is a combination of the seven different colors.

According to the question the correct option will be ‘B’ because the Convex mirrors arecommonly 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.

According to the question the correct option will be ‘C’ because Fora convex mirror, the radius of curvature R, is twice its focal length f.

R=2f

30=2f

f=15

Therefore, the focal length f=15 cm

According to the question thecorrect option will be ‘B’ because the colors in the rainbows are labeled as VIBGYOR.

VIBGYOR stand for violet, indigo, blue, green,yellow, orange and red.

Accordingto the question the correct option will be ‘A’ because The bouncing back oflight from a shiny surface without absorption of it is called as reflection.Reflection always follows certain laws called the laws of reflection. The lawsare as follows:
1. Angle of incidence is equal to the angle of reflection.
2. The incident ray, normal and the reflected ray lie in the same plane.

According to the question the correct option will be ‘A’ because When white light is passed through a prism, it splits into seven different colors namely, red,orange, yellow, green, blue, indigo and violet. If we do the reverse, that is mix the beams of light of all color, white light is obtained.

According to the question the correct option will be ‘A’ because 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 spoonacts as a concave mirror and the outer surface of the spoon acts as a convex mirror.

According to the question the correct option will be ‘D’ because Image formed by a plane mirror is laterally inverted and therefore the letters get inverted about thevertical axis.

Aword that is horizontally symmetrical about its centre letter would read thesame in a mirror.

According to the question the correct option will be ‘C’ because The letter "I” in "VIBGYOR” represents the color "indigo”. VIBGYOR stand for violet, indigo, blue, green, yellow, orange and red.

According to the question the correct option will be ‘B’ because When the object is keptin between focus and the pole, a concave mirror forms an enlarged, virtual anderect image. A convex mirror always forms diminished virtual image. A plane mirror always forms a virtual and erect image without any magnification.