Light and Optics

Free sample questions

Light and Optics — sample Science questions with answers

1. Question 1

   Which of the following phenomena proves that light travels in a straight line?

   • AFormation of shadows behind opaque objects
   • BRefraction of a spoon in a glass filled with water
   • CFormation of a rainbow in the sky after rain
   • DThe sky appears blue at noon

   Answer: A. Formation of shadows behind opaque objects

   Light travels in a straight line and cannot penetrate opaque objects. This causes the formation of dark areas or shadows behind the object.

2. Question 2

   What is the approximate speed of light when travelling through air or vacuum?

   • A$3\times 10^8\text{ m/s}$
   • B$3\times 10^5\text{ m/s}$
   • C$340\text{ m/s}$
   • D$1.5\times 10^8\text{ m/s}$

   Answer: A. $3 \times 10^8 \text{ m/s}$

   The speed of light in vacuum or air is very high, approximately $3\times 10^8\text{ m/s}$.

3. Question 3

   Based on the Law of Reflection, if the angle of incidence ($i$) of a light ray striking a plane mirror is $35^{\circ }$, what is the value of the angle of reflection ($r$)?

   • A$35^{\circ }$
   • B$55^{\circ }$
   • C$90^{\circ }$
   • D$70^{\circ }$

   Answer: A. $35^{\circ}$

   According to the Law of Reflection, the angle of incidence ($i$) is always equal to the angle of reflection ($r$). Hence, $r=i=35^{\circ }$.

4. Question 4

   Which of the following correctly describes the characteristics of an image formed by a plane mirror?

   • AVirtual, upright, laterally inverted, and same size as the object
   • BReal, inverted, laterally inverted, and magnified
   • CVirtual, upright, not laterally inverted, and diminished
   • DReal, upright, laterally inverted, and same size as the object

   Answer: A. Virtual, upright, laterally inverted, and same size as the object

   The image formed by a plane mirror has the characteristics: virtual (cannot be formed on a screen), upright, laterally inverted, and the image distance is equal to the object distance, while the image size is also equal to the object size.

5. Question 5

   Convex mirrors are often used at sharp road bends or in supermarkets. What is the main advantage of using this type of mirror?

   • AIt provides a wider field of view to the driver
   • BIt allows the formed image to appear larger and clearer
   • CIt focuses sunlight to illuminate dark areas
   • DIt produces a real image that can be projected onto a screen

   Answer: A. It provides a wider field of view to the driver

   Convex mirrors curve outward, causing light rays to diverge and providing a wider field of view compared to plane mirrors, even though the resulting image is smaller than the original object.