Q.1
Out of the following options which one can be used to produce a propagating electromagnetic wave ?
  • a) A charge moving at constant velocity
  • b) A stationary charge
  • c) A charge less particle
  • d) An accelerating charge
Q.2
A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it. … [ IIT main 2013]
  • a) 10.62 MHz
  • b) 10.62 kHz
  • c) 5.31 MHz
  • d) 5.31 kHz
Q.3
The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is …[ IIT Mains 2013]
  • a) 3 V/m
  • b) 6 V/m
  • c) 9 V/m
  • d) 12 V/m
Q.4
The energy of X-ray photon is 3.3 ×10⁻¹⁶ J its frequency is
  • a) 2 × 1019 Hz
  • b) 5 × 1018 Hz
  • c) 5 × 1017 Hz
  • d) 5 × 1016 Hz
Q.5
If the electric field asssociated with a radiation of frequency 10 MHz is E=10sin( kx -ωt) mV/m . then its energy density in J/m3 is [ εo=8.85×10⁻¹²C2N-1m-2]
  • a) 4.425×10⁻¹⁶
  • b) 6.26×10⁻¹⁴
  • c) 8.85×10⁻¹⁶
  • d) 8.85×10⁻¹⁴
Q.6
The etensity of plane electromagnetic wave with Bo=1.0×10⁻⁴T in W/m2 is ..
  • a) 2.38×106
  • b) 1.19×106
  • c)6×105
  • d)4.76×106
Q.7
The magnetic field of an electromagnetic plane travelling along the negative X-direction is given by By=2×10⁻⁷ sin(0.5×103 x + 1.5×1011 t ) T what is the wavelength and frequecy of the wave
  • a) 1.26 m, 23.9 Hz
  • b) 2.56 cm, 12.0 GHz
  • c)3.21 m , 36.2 GHz
  • d)1.26 cm, 23.9 GHz
Q.8
The maximum value of E in an electromagnetic waves in air is equal to 6.0×10⁻⁴ Vm . The maximum value of B is ____________
  • a) 1.8×105 T
  • b) 2×104 T
  • d)1.8×1013 T
  • c)2×10⁻¹² T
Q.9
The magnetic field in a plane electromagnetic wave is given By=2×10⁻⁷ sin ( 0.5×103x + 1.5×1011t) T
  • a) Ex=60 sin ( 0.5×103x + 1.5×1011t) V/m
  • b) Ez=60 sin ( 0.5×103x + 1.5×1011t) V/m
  • c) Ex=60 sin ( 1.5×103x + 0.5×1011t) V/m
  • d) Ex=60×1015 sin ( 1.5×103x + 0.5×1011t) V/m
Q.10
A TV tower has height of 100m. How much population is covered by the TV broadcast if the average population density around the tower is 1000km-2> ( radius of earth=6.37× 106m) [ AFMC 2009]
  • a) 4 lakh
  • b) 4 billion
  • c) 40,000
  • d) 40 lakh
Q.11
The frequency of e.m. wave which is best suited to observe a particle of radius 3×10⁻⁴ cm is of the order of [ CBSE 1993]
  • a) 1015
  • b) 1014
  • c)1013
  • d)1012
Q.12
The Sun delivers 103 W/m2 of electromagnetic flux to the earth's surface. that is incident on a roof of dimensions 8m×20m . the radiation force on the roof will be
  • a)8.53×10⁻⁵ N
  • b) 2.3×10⁻³ N
  • c)1.33×10⁻³ N
  • d)5.33×10⁻⁴ N
Q.13
A plane electromagnetic wave of wave intensity 6W/m2 strikes a small mirror of area 30cm2, held perpendicular to a approching wave. The momentum trasmitted in kgm/s by the wave to the mirror each second will be
  • a) 0.6 ×10⁻¹⁰
  • b) 2.4 ×10⁻⁹
  • c)3.6 ×10⁻⁸
  • d)4.8×10⁻⁷
Q.14
A plane electromagnetic wave of wave intensity 10 wm-2 strikes a small mirror ofarea 20 cm2 , held perpendicular to the approaching wave. The radiation force onthe mirror will be
  • a)6.6×10⁻¹¹ N
  • b)1.33×10⁻¹¹ N
  • c)1.33×10⁻¹⁰ N
  • d)6.6×10⁻¹⁰ N
Q.15
Light with an energy flux of 25 × 104Wm–2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm2, the average force exerted on the surface is … [AIPMT 2014]
  • a) 1.20 × 10⁻⁶ N
  • b) 3.0 × 10⁻⁶ N
  • c) 1.25 × 10⁻⁶ N
  • d) 2.50 × 10⁻⁶ N
Q.16
In an electromagnetic wave in free space the root mean square value of the electric field is Erms= 6 V/m. The peak value of the magnetic field is
  • a) 1.41 × 10⁻⁸ T
  • b) 2.83 × 10⁻⁸ T
  • c) 0.70 × 10⁻⁸ T
  • d) 4.23 × 10⁻⁸ T
Q.17
A pulse of light of duration 100 ns is absorbed completely by a small object initially at rest. Power of the pulse is 30 mW and the speed of light is 3 × 108 ms−The final momentum of the object is
  • a) 0.3 × 10⁻¹⁷ kg ms−1
  • b) 1.0 × 10⁻¹⁷ kg ms−1
  • c) 3.0 × 10⁻¹⁷ kg ms−1
  • d) 9.0 × 10⁻¹⁷ kg ms−1
0 h : 0 m : 1 s