Q20 (CDS-I/2022) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Thermal physics Answer Verified

Which one of the following statements is true with regard to a greenhouse ?

The shorter wavelength infrared radiations from the Sun can enter into the greenhouse while longer wavelength infrared radiations from the ground and the plants inside the greenhouse cannot pass back out through the glass.

The shorter wavelength infrared radiations from the Sun can enter into the greenhouse and the longer wavelength infrared radiations from the ground and the plants inside the greenhouse can also pass back out through the glass.

The shorter wavelength infrared radiations from the Sun cannot enter into the greenhouse while longer wavelength infrared radiations from the ground and the plants inside the greenhouse can pass back out through the glass.

No infrared radiation can pass through the glass of the greenhouse.

Result

Your answer: — · Correct: A

Explanation

A greenhouse operates on the principle of selective transparency of glass to different wavelengths of radiation. Glass is transparent to incoming short-wavelength solar radiation, which includes visible light and near-infrared radiation from the Sun [5]. Once this radiation enters the greenhouse, it is absorbed by the ground and plants, which then re-emit the energy as long-wavelength (thermal) infrared radiation [4]. Unlike the incoming short-wave radiation, glass is largely opaque to this outgoing long-wave radiation, effectively trapping the heat inside [1]. While modern physics notes that the suppression of convection (preventing warm air from escaping) is a major factor in actual greenhouses, the radiative mechanism described—where short-wave infrared enters but long-wave infrared is blocked—remains the standard scientific explanation for the 'greenhouse effect' analogy [1].

Sources

[1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Global Warming > p. 96
[5] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > The Passage of Solar Radiation through the Atmosphere > p. 68
[2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Greenhouse Effect and Global Warming > p. 7
[3] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Role of Greenhouse Gases > p. 255
[4] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 13: Our Home: Earth, a Unique Life Sustaining Planet > A step further > p. 214

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Which one of the following statements is true with regard to a greenhouse ?

Explanation

SIMILAR QUESTIONS

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