Physics MCQs
Topic Notes: Physics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
Under what conditions does the principle of rectilinear propagation of light hold true?
Answer:
Homogeneous and transparent
The rectilinear propagation of light, which states that light travels in a straight line, is valid only when the medium through which the light passes is homogeneous and transparent. In a homogeneous medium, the refractive index is constant throughout, preventing the bending or refraction of light rays that would otherwise occur in non-uniform media.
2
According to the law of reflection, how does the angle of incidence compare to the angle of reflection?
Answer:
equal
The law of reflection states that when a light ray strikes a smooth surface, the angle of incidence (the angle between the incident ray and the normal) is always equal to the angle of reflection (the angle between the reflected ray and the normal).
3
Which of the following statements regarding the image produced by a plane mirror is incorrect?
Answer:
It is real image
A plane mirror always forms a virtual, erect, and laterally inverted image. Because the light rays do not actually converge at the image position but only appear to diverge from it, the image is classified as virtual, not real. Therefore, the statement that it is a real image is false.
4
Which of the following statements accurately describes the properties of an image formed by a plane mirror?
Answer:
The image is virtual, erect and laterally inverted
A plane mirror produces an image that is virtual (cannot be caught on a screen), erect (upright), and laterally inverted (left appears as right). The size of the image is identical to the object size.
5
What is the necessary orientation of the observer relative to the Sun and raindrops to view a rainbow?
Answer:
The Sun remains behind us and we face the raindrops
To see a rainbow, sunlight must enter the water droplets from behind the observer. The light undergoes internal reflection and refraction within the droplets before exiting toward the observer's eyes. Therefore, the observer must have the Sun at their back and face the region of the sky where the rain is falling.
6
What term describes materials that allow light to pass through, but not clearly enough to see distinct objects?
Answer:
Translucent
Translucent materials allow some light to pass through but scatter the light rays in different directions. This prevents the formation of a clear image, making objects behind the material appear blurred or indistinct.
7
What is the phenomenon called when light traveling through one medium strikes the surface of another and returns into the original medium?
Answer:
reflection
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. This process follows the law of reflection, where the angle of incidence equals the angle of reflection relative to the surface normal.
8
How would a blue-colored book appear when illuminated exclusively by monochromatic red light?
Answer:
black
The color of an object is determined by the light it reflects. A blue book appears blue because it absorbs most wavelengths of visible light and reflects blue light. When illuminated by monochromatic red light, there is no blue light to reflect. Since the book absorbs the red light, it reflects almost no light back to the observer, making it appear black.
9
Which optical principle states that the incident ray, the reflected ray, and the normal at the point of incidence all reside in the same plane?
Answer:
reflection
The law of reflection states two main points: the angle of incidence equals the angle of reflection, and the incident ray, the reflected ray, and the normal all lie in the same plane.
10
A convex mirror focal length f (in air), is immersed in a fluid $$\left( {\mu = \frac{4}{3}} \right)$$ . The focal length of the mirror in liquid will be-
Answer:
$$\left( {\frac{4}{3}} \right)f$$
Source answer preserved: option B ($$\left( {\frac{4}{3}} \right)f$$). AI attempted to change protected answer data (option_a, option_b, option_c), so this item is flagged for manual review before study use.