Match List - I with List - II.
| List – I EM waves | List – II Wavelength Range | ||
|---|---|---|---|
| (A) | Light | (I) | 1 nm to \( 10^{-3} \) nm |
| (B) | Infra-red | (II) | 700 nm to 400 nm |
| (C) | X-rays | (III) | 400 nm to 1 nm |
| (D) | UV rays | (IV) | 1 mm to 700 nm |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A)-(II), (B)-(IV), (C)-(I), (D)-(III)
The electromagnetic spectrum is arranged by wavelength: from long to short it runs radio, microwave, infra-red, light, ultraviolet, X-rays, gamma rays.
(A) Light — this matches (II) 700 nm to 400 nm. This is the visible range, from red at the long end to violet at the short end.
(B) Infra-red — this matches (IV) 1 mm to 700 nm. It lies just beyond the red end of the visible range, with wavelengths longer than 700 nm.
(C) X-rays — this matches (I) 1 nm to \( 10^{-3} \) nm. X-rays have very short wavelengths, from about 1 nm down to \( 10^{-3} \) nm.
(D) UV rays — this matches (III) 400 nm to 1 nm. They lie just beyond the violet end of the visible range.
NCERT (2026-27):
Gamma Rays – “… Table 8.1 summarises different types of electromagnetic waves, their production and detections. As mentioned earlier, the demarcation between different regions is not sharp and there are overlaps.”
| Type | Wavelength range | Production | Detection |
|---|---|---|---|
| Radio | > 0.1 m | Rapid acceleration and decelerations of electrons in aerials | Receiver’s aerials |
| Microwave | 0.1m to 1 mm | Klystron valve or magnetron valve | Point contact diodes |
| Infra-red | 1mm to 700 nm | Vibration of atoms and molecules | Thermopiles Bolometer, Infrared photographic film |
| Light | 700 nm to 400 nm | Electrons in atoms emit light when they move from one energy level to a lower energy level | The eye Photocells Photographic film |
| Ultraviolet | 400 nm to 1nm | Inner shell electrons in atoms moving from one energy level to a lower level | Photocells Photographic film |
| X-rays | 1nm to 10-3 nm | X-ray tubes or inner shell electrons | Photographic film Geiger tubes Ionisation chamber |
| Gamma rays | <10-3 nm | Radioactive decay of the nucleus | -do- |