Directions: In the following questions, a statement of assertion (A) ...
In tube light, the gas contains vapour of metals. In metallic atoms, electronic transition occurs due to which light of a particular wavelength is emitted. So emission of whit light is due to electronic transition and not due to vibration of atoms as in hot substance. SO, assertion is true but reason is false.
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Directions: In the following questions, a statement of assertion (A) ...
Assertion: A tube light emits white light.
Reason: Emission of light in a tube takes place at a very high temperature.
The correct answer is option 'C' - Assertion (A) is true but reason (R) is false.
Explanation:
Reasoning behind the correct answer:
1. A tube light emits white light:
A tube light is a type of fluorescent lamp that produces visible light by using electricity to excite mercury vapor. The mercury vapor emits ultraviolet (UV) light, which then causes a phosphor coating on the inside of the tube to fluoresce and emit visible light. This visible light is usually in the form of white light, although variations of tube lights can emit light of different colors.
2. Emission of light in a tube takes place at a very high temperature:
This reason is incorrect. In a fluorescent tube light, the emission of light does not occur due to high temperature. Instead, it occurs due to a process called fluorescence. When an electric current passes through the tube, it excites the mercury vapor, causing it to emit UV light. The UV light then interacts with the phosphor coating, causing it to emit visible light. The process does not involve high temperatures, but rather the excitation of electrons in the mercury vapor.
Conclusion:
The assertion is true because a tube light does emit white light. However, the reason given for this assertion is false. The emission of light in a tube light does not occur at a very high temperature but rather through the process of fluorescence. Therefore, option 'C' is the correct answer.
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