EM Waves MCQs : Electromagnetic waves constitute electric and magnetic fields, both produced by accelerating charges. When a charged particle accelerates in oscillatory motion, it causes oscillations in its electric field and magnetic field produced by it. Let’s understand the concept of electromagnetic waves!
EM Waves MCQs
EM Waves MCQs
Q.1: What is wavelength of signal weather frequency of 300 megahertz?
[A] 2m
[B] 20m
[C] 10m
[D] 1m
[D] 1m
Q.2: If𝜆𝑥 , 𝜆𝑚 , 𝜆𝑣 represents wavelength of X-Rays, microwaves & visible rays then
[A] 𝜆𝑚 > 𝜆𝑥 > 𝜆𝑣
[B] 𝜆𝑚 > 𝜆𝑣 > 𝜆𝑥
[C] 𝜆𝑣 > 𝜆𝑥 > 𝜆𝑚
[D] 𝜆𝑣 > 𝜆𝑚 > 𝜆𝑥
[B] 𝜆𝑚 > 𝜆𝑣 > 𝜆𝑥
Q.3: Human body radiate
[A] microwave
[B] X-rays
[C] infrared rays
[D] gamma rays.
[C] infrared rays
Q.4: Properties of EM radiation are identified by using there:
[A] colour
[B] their use
[C] speed
[D] frequency or wavelength
[D] frequency or wavelength
Q.5: Which of the following transport by EM waves:
[A] charge & momentum
[B] frequency & wavelength
[C] energy & momentum
[D] wavelength & energy
[C] energy & momentum
Q.6: One requires 11eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in
[A] visible region.
[B] infrared region.
[C] ultraviolet region.
[D] microwave region.
[C] ultraviolet region.
E = hν = 11 × 1.6×10−19 = 6.626×10−34 × ν ⇒ ν = 2.656×1015 Hz This frequency belongs to UV region.
Q.7: Light with an energy flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence. If the surface has an area of 30 cm2, the total momentum delivered (for complete absorption) during 30 minutes is
[A] 36 × 10–5 kg m/s.
[B] 36 × 10–4 kg m/s.
[C] 108 × 104 kg m/s.
[D] 1.08 × 107 kg m/s.
[B] 36 × 10–4. kg m/s.
E = power × time = =20 × 30 × 30 × 60 = 1.08 × 106 J
Momentum (p) = E / c = 1.08 × 106 / 3 × 108 = 36 × 10-4 kgm/s
Q.8: The electric field intensity produced by the radiations coming from 100 W bulb at a 3 m distance is E. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is
[A] E/2
[B] 2E
[C] E / √ 2
[D] √2 E
[A] E/2
Q.9: If E and B represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along
[A]
E
[B]
B⃗
[C]
E ⃗ × B ⃗
[D]
B⃗ × E⃗
E⃗ × B⃗