Assertion (A): If one half of a mirror is covered by an opaque material, then only half image of the object is formed.
Reason (R): By covering one half of the mirror, focal length of mirror will be halved.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Covering half a mirror reduces the intensity of the image but a complete image is still formed. The focal length of a mirror depends only on its radius of curvature, not on the aperture or how much of its surface is exposed.
Assertion (A): In medical technology endoscopy, optical fibres are used to facilitate visual examination of internal organs of the body.
Reason (R): Optical fibres are fabricated so that there should be very less absorption of light and hence no appreciable loss of light intensity.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Optical fibers are indeed used in endoscopy to transmit light for internal examination. This is possible because they are designed for very low light absorption, ensuring minimal loss of light intensity over their length. Both statements are true and R explains A.
Assertion (A): When white light passes successively through two identical prisms, one inverted with respect to other, then in emergent side, again white light is obtained.
Reason (R): Prism has no ability to create colour but it only separates the colours already present in white light.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true; the second inverted prism recombines the dispersed light back into white light. Reason (R) is true; prisms only disperse existing colours, they do not create new ones. Reason (R) correctly explains Assertion (A).
Assertion (A): Secondary rainbow is fainter than primary rainbow.
Reason (R): Secondary rainbow is seen due to the scattering of primary rainbow through water molecules.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true; secondary rainbows are fainter due to two internal reflections causing more light loss. Reason (R) is false; secondary rainbows result from light undergoing two internal reflections in raindrops, not scattering of a primary rainbow.
Assertion (A): In clear weather, sky appears to be blue not violet.
Reason (R): In clear atmosphere, light of shorter wavelength is scattered more as compared to light of longer wavelength.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true; violet light scatters most, but our eyes are more sensitive to blue. Reason (R) is true; Rayleigh scattering is inversely proportional to the fourth power of wavelength, scattering shorter wavelengths more effectively. Reason (R) correctly explains Assertion (A).
Assertion (A): During sunset and sunrise sun appears to be red.
Reason (R): During sunrise or sunset, sun emits electromagnetic radiations of comparatively higher wavelength only.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true; at sunrise/sunset, sunlight travels longer through the atmosphere, scattering away shorter wavelengths (blue) and leaving longer wavelengths (red). Reason (R) is false; the sun emits all wavelengths. The perceived color is due to atmospheric scattering, not selective emission.
Assertion (A): Iris of the eye contains rods and cones which transmits electric signal to brain through optic nerve.
Reason (R): Rods sense colour of object and cone sense intensity of light.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Both Assertion (A) and Reason (R) are false. Rods and cones are located in the retina, not the iris. Rods detect light intensity (dim light), and cones detect color (bright light).
Assertion (A): A virtual image can’t be caught on screen, yet we see a virtual image. We are obviously bringing it on to the screen, i.e. the retina.
Reason (R): The retina is a special type of screen present in the back of eye consisting of nerve fibre which can catch both real & virtual image.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true; virtual images cannot be projected onto a physical screen. Reason (R) is false; the retina, acting as a screen, can only detect real images formed by the eye's lens. Our brain interprets virtual images.
Assertion (A): In a magnifying glass, the angle subtended by an object at the eye is equal to the angle subtended by its virtual image at the eye. Still the magnifying glass provides angular magnification.
Reason (R): Magnifying glass produce a virtual magnified image of the object.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is false. Angular magnification occurs precisely because the virtual image subtends a larger angle at the eye than the object alone. Reason (R) is true; a magnifying glass (convex lens) forms a virtual, upright, and magnified image.
Assertion (A): Concave mirror can’t form virtual image of a virtual object.
Reason (R): Convex mirror can’t form real image of a real object.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Both Assertion (A) and Reason (R) are false. A concave mirror can form a virtual image of a virtual object if the object is between its pole and focus. A convex mirror can form a real image of a virtual object, for example, if the virtual object is placed between its pole and focus.