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The refractive indices of three media are given below: A ray of light is travelling from A to B and another ray is travelling from B to C. (a) In which of the two cases the refracted ray bends towards the normal? (b) In which case does the speed of light increase in the second medium? Give reasons for your answer.
(a) When a ray travels from A (refractive index 1.6) to B (1.8), it moves from a rarer to a denser medium. In this case, the speed of light decreases, causing the ray to bend towards the normal. Therefore, the bending towards the normal occurs only in the transition from medium A to medium B. (b) WhRead more
(a) When a ray travels from A (refractive index 1.6) to B (1.8), it moves from a rarer to a denser medium. In this case, the speed of light decreases, causing the ray to bend towards the normal. Therefore, the bending towards the normal occurs only in the transition from medium A to medium B.
(b) When the ray moves from B (refractive index 1.8) to C (1.5), it passes from a denser to a rarer medium. Light travels faster in a medium with lower refractive index. Thus, in medium C, with refractive index 1.5, the speed of light increases compared to medium B, because of the inverse relationship between refractive index and velocity.
See lessAssertion (A): Rusting of Iron is endothermic in nature. Reason (R): As the reaction is slow, the release of heat is barely evident.
Rusting of iron occurs when iron reacts with oxygen and moisture, forming hydrated iron oxide. This reaction is exothermic, though very slow, so heat release is hardly noticed. Therefore, the statement that rusting is endothermic is false, while the reason provided is also incorrect. Thus, the correRead more
Rusting of iron occurs when iron reacts with oxygen and moisture, forming hydrated iron oxide. This reaction is exothermic, though very slow, so heat release is hardly noticed. Therefore, the statement that rusting is endothermic is false, while the reason provided is also incorrect. Thus, the correct answer is C. Assertion is true but Reason is false.
See lessWhich of the following features relates to biodegradable substances? (a) Broken down by biological processes (b) Remain inert (c) Persist in environment for long time (d) May harm the ecosystem
The correct answer is: (a) Broken down by biological processes. Biodegradable substances are materials that can be naturally broken down by bacteria, fungi, or other living organisms into harmless products. Examples include food waste, paper, and leaves. They don’t accumulate in the environment andRead more
The correct answer is: (a) Broken down by biological processes. Biodegradable substances are materials that can be naturally broken down by bacteria, fungi, or other living organisms into harmless products. Examples include food waste, paper, and leaves. They don’t accumulate in the environment and are eco-friendly, unlike non-biodegradable substances that persist and harm ecosystems.
See lessIn 1987, an agreement was formulated by the United Nations Environment Programme (UNEP) to freeze the production of “X” to prevent depletion of “Y”. “X” and “Y” respectively referred here are:
The correct answer is: (c) CFCs; Ozone. In 1987, the Montreal Protocol was signed under the United Nations Environment Programme (UNEP). It aimed to freeze the production of CFCs (chlorofluorocarbons) because they were damaging the ozone layer in the atmosphere, which protects the Earth from harmfulRead more
The correct answer is: (c) CFCs; Ozone. In 1987, the Montreal Protocol was signed under the United Nations Environment Programme (UNEP). It aimed to freeze the production of CFCs (chlorofluorocarbons) because they were damaging the ozone layer in the atmosphere, which protects the Earth from harmful ultraviolet (UV) rays. This helped prevent further ozone depletion.
See lessWhen light enters the atmosphere it strikes on extremely fine particles, which deflect the rays of light in all possible directions, This is due to – (a) reflection of light (b) atmospheric refraction (c) scattering of light (d) dispersion of light
The correct answer is: (c) scattering of light. When sunlight enters the atmosphere, it meets tiny particles like dust and gas molecules. These particles scatter the light in all directions, rather than just letting it pass straight. This phenomenon is called scattering of light, which is also why tRead more
The correct answer is: (c) scattering of light. When sunlight enters the atmosphere, it meets tiny particles like dust and gas molecules. These particles scatter the light in all directions, rather than just letting it pass straight. This phenomenon is called scattering of light, which is also why the sky looks blue during the day.
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