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Physics · 2025 · 3 marks
CBSE 2025 · Region 2 · Set 1 · Q25
(a) The electric field E of an electromagnetic wave propagating in north direction is oscillating in up and down direction. Describe the direction of…
(a)
The electric field $\displaystyle \overrightarrow{\mathrm{E}}$ of an electromagnetic wave propagating in north direction is oscillating in up and down direction. Describe the direction of magnetic field $\displaystyle \overrightarrow{\mathrm{B}}$ of the wave.
(b)
Are the wave length of radio waves and microwaves longer or shorter than those detectable by human eyes?
(c)
Write main use of each of the following in human life:
(i)
Infrared waves (ii) Gamma rays
Marking-scheme solution
(a)
Magnetic field oscillates in the east-west direction as it is mutually perpendicular to the direction of electric field.
(b)
Wavelength of the radiowaves and microwaves is longer than visible light.
(c)(i)
Use of infrared waves:
Used for physical therapy.
Used for maintaining average temperature of the earth.
Used in Earth satellites for military purposes & to observe growth of crops.
Used in remote control.
(ii)
Use of Gamma rays:
Used in treatment of cancer.
Used in diagnostic imaging.
Used to sterilize medical equipment.
All Electromagnetic Waves questions2025 question paperNCERT solutions: Electromagnetic WavesPractice Electromagnetic Waves →
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CBSE Class 12 Physics past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.