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Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): The focal length of a concave mirror is f and an object is placed at a distance x from the focus. The magnification produced by the mirror is f/x.
Reason (R): magnification = size of image / size of object
Using mirror formula,
1/v+1/u = 1/f
Or, 1/v – 1/(f+x) = – 1/f
∴ v = – f(f+x)/x
Magnification (m) = size of image / size of object = – v/u
So, the assertion and reason both are true and the reason properly explains the assertion.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Air bubbles shine in water.
Reason (R): Air bubbles shine in water due to refraction of light.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): A double convex air bubble is formed within a glass slab. The air bubble behaves like a converging lens.
Reason (R): Refractive index of glass is more than the refractive index of air.
When a double convex air bubble is formed within a glass slab, the refractive index of the medium of the bubble is less than the refractive index of the surrounding medium. Hence the lens will not behave like a converging lens. It will behave like a diverging lens. So, the assertion is false.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): A convex lens of focal length 30 cm can’t be used as a simple microscope in normal setting.
Reason (R): For normal setting, the angular magnification of simple microscope is M = D/f.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): Convex lens behaves like a simple microscope.
Reason (R): For larger magnifying power, the focal length of convex lens should be small.
The magnifying power of a convex lens is expressed as:
For least distance of distinct vision,
Since f is in the denominator, for larger magnifying power, focal length should be small. So, the reason is also correct and it is the assertion.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): A convex mirror cannot form real images.
Reason (R): Convex mirror converges the parallel rays that are incident on it.
Parallel rays incident on convex mirror do not actually meet. They get reflected in such a manner that their extension meet at a point. So, the reason is false.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): The mirror formula 1/v + 1/u = 1/f is valid for mirrors of small aperture.
Reason (R): Laws of reflection of light is valid for only plane surface and not for large spherical surface.
Laws of reflection are valid for any surface plane or spherical. Hence the reason is false.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): A diamond of refractive index √6 is immersed in a liquid of refractive index √3 . If light travels from diamond to liquid, total internal reflection will take place when angle of incidence is 30°.
Reason (R): µ = 1/sin C, where µ is the refractive index of diamond with respect to the liquid
For total internal reflection, angle of incidence should be greater that critical angle.
Since angle of incidence is 30°, total internal reflection cannot take place.
So, the assertion is false. But the reason is true.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): The scattering of light while passing through a true solution is called Tyndall effect.
Reason (R): Intensity of scattered light is inversely proportional to the fourth power of wavelength.
In Rayleigh scattering intensity of scattered light is inversely proportional to the fourth power of wavelength, blue light is scattered much more strongly than red light. Hence the reason is true.
Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
Assertion (A): If the objective lens and the eyepiece lens of a microscope are interchanged, it works as a telescope.
Reason (R): Objective lens of telescope require large focal length and eyepiece lens require small focal length.
Hence, if the objective lens and the eyepiece lens of a microscope are interchanged that will not meet the criterion of the telescope.
So, the reason is true. But the assertion is false.
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157 videos|452 docs|213 tests
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