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Electromagnetic Waves · Question 41

AIPMT 2003MCQEasy📈 Topic in 38% papers+4−1
1

We consider the radiation emitted by the human body. Which one of the following statements is true?

  1. The radiation emitted is in the infra-red region
  2. The radiation emitted only during the day
  3. The radiation is emitted during the summers and absorbed during the winters
  4. The radiation emitted lies in the ultraviolet region and hence is not visible

Answer

(1) The radiation emitted is in the infra-red region

Solution

Every body above absolute zero emits thermal radiation at all times (day and night, summer and winter).

By Wien's displacement law, m T = b 2.9 10-3 m K

For the human body, T 310 K

⇒ m = 2.9 10-3310 9.4 10-6 m 9400 nm

As per NCERT, warm bodies such as the human body emit infrared (heat) radiation.

∴ The radiation emitted by the human body is in the infra-red region.

Answer: (1)

AIPMT 2003

Keep practising — Electromagnetic Waves

2

Which of the following rays are not electromagnetic waves?

  1. X-rays
  2. -rays
  3. -rays
  4. heat rays
AIPMT 2003
3

The velocity of electromagnetic wave is parallel to

  1. B E
  2. E B
  3. E
  4. B
AIPMT 2002
4

What is the cause of greenhouse effect?

  1. infra-red rays
  2. ultra violet rays
  3. X-rays
  4. radio waves.
AIPMT 2002
5

Biological importance of ozone layer is

  1. it stops ultraviolet rays
  2. ozone layer reduces greenhouse effect
  3. ozone layer reflects radio waves
  4. ozone layer controls O2/H2 ratio in atmosphere
AIPMT 2001
6

The frequency order for -rays (a), X-rays (b), UV rays (c) is

  1. b > a > c
  2. a > b > c
  3. c > b > a
  4. a > c > b
AIPMT 2000

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