Light & Optics MCQs with Answers

The refractive index of glass is 1.5. The speed of light in air is 3 × 10⁸ m/s. What will be the speed of light in the glass?

• A.2 × 10⁸ m/s
• B.1.5 × 10⁸ m/s
• C.4.5 × 10⁸ m/s
• D.3 × 10⁸ m/s

Sky looks blue in colour because it absorbs _?

• A.Blue and reflects others
• B.All colours except blue
• C.Only red and green
• D.None of these

Which prism is one of the most commonly used dispersive prisms?

• A.Triangular prism
• B.Rectangular prism
• C.Pentagonal prism
• D.Hexagonal prism

The image formed in a plane mirror is?

• A.Virtual, upright, same size
• B.Real, inverted, diminished
• C.Virtual, inverted, magnified
• D.Real, upright, same size

Which of the following regions of the spectrum would be used to determine the structure of crystalline solids?

• A.Microwaves
• B.Infrared
• C.Ultraviolet
• D.X-rays

The focal length of the objective and eyepiece of an astronomical telescope are?

• A.50 cm and 5 cm
• B.5 cm and 50 cm
• C.50 cm and 50 cm
• D.5 cm and 5 cm

Which of the following colours is not seen in a rainbow?

• A.Red
• B.Green
• C.Brown
• D.Violet

Concave lens causes rays to _?

• A.Converge
• B.Reflect
• C.Diverge
• D.Polarize

In Young's double slit experiment, if slit separation is halved and screen distance is doubled, fringe width becomes?

• A.Two times
• B.Four times
• C.Half
• D.Remains unchanged

What does reflection refer to in scientific terms?

• A.The bending of light when it passes through a medium
• B.The bouncing back of light when it hits a surface
• C.The splitting of light into its constituent colors
• D.The absorption of light by a dark surface