Question:
Consider the following statements:
(1) A concave mirror always forms a real image.
(2) A real image cannot be obtained on a screen.
(3) A concave lens always forms a virtual image.
(4) White light is composed of seven colours.
Choose the correct answer from the options given below:
(A) (1) and (2) only
(B) (2) and (4) only
(C) (3) and (4) only
(D) (1) and (3) only
answer :
Analysis of the Statements
- (1) A concave mirror always forms a real image.
- Incorrect. A concave mirror forms a real image only when the object is placed beyond the focal point. When the object is placed between the pole and the focal point, it forms a virtual, erect, and magnified image (e.g., a shaving or makeup mirror).
- (2) A real image cannot be obtained on a screen.
- Incorrect. This is the opposite of the definition. A real image is formed where light rays physically converge, and its key characteristic is that it can be obtained on a screen. For example, the image formed by a cinema projector on the screen is a real image.
- (3) A concave lens always forms a virtual image.
- Correct 👍. A concave lens is a diverging lens. Regardless of the object’s position, it always spreads out light rays to form a virtual, erect, and diminished (smaller) image.
- (4) White light is composed of seven colours.
- Correct 👍. As demonstrated by Isaac Newton, when white light passes through a prism, it undergoes dispersion and splits into a spectrum. This spectrum is conventionally divided into seven main colors: Violet, Indigo, Blue, Green, Yellow, Orange, and Red (VIBGYOR).