Q.1.
An antenna behaves as resonant circuit only when its length is
-
50%
a)λ/2
-
0%
b) λ/4
-
0%
c)λ
-
50%
d)λ/2 or integral multiple of λ/2
Q.2.
Broadcasting antenna are generally
-
0%
a) Omnidirectinal type
-
50%
b) vertical type
-
50%
c)horizontal type
-
0%
d)none of the above
Q.3.
The number of telephonic messages which are carried by a fiber at an instant with much less intensity loss are
-
25%
a) 2400
-
50%
b) 2200
-
25%
c)2000
-
0%
d)1800
Q.4.
The main objective of an optical source is
-
0%
a) to demodulate the electrical signal
-
25%
b) to detect the signal
-
50%
c) to convert the electrical energy into an optical energy
-
25%
d) all of these
Q.5.
In X-ray tube the accelerating potential applied at anode is V volt. The minimum wavelength of the emitted X-ray will be
-
0%
a)eV / h
-
50%
b) h / eV
-
25%
c)eV / ch
-
25%
d)hc / eV
Q.6.
Electromagnetic waves are produced by
-
75%
a) an accelerating charge
-
0%
b) a static charge
-
0%
c)chargeless particle
-
25%
d)a moving charge
Q.7.
An electromagnetic wave going through vaccum is described by E=Eo sin(kx - ωt)Which of the following is / are independent of wavelength
-
0%
a) k
-
25%
b) k/ω
-
50%
c)kω
-
25%
d)ω
Q.8.
A compass needle is placed in the gap of parallel plate capacitor. The capacitor is connected to battery through a resistance. The compass needle
-
50%
a) deflection and gradually comes to the original position in a time which is large compared to the time constant
-
50%
b) does not deflect
-
0%
c) deflects and remains deflected as long as the battery is connected
-
0%
d) deflects for a very short time and then comes back to the original position
Q.9.
The energy contained in small volume through which an electromagnetic wave is passing oscillates with
-
50%
a)double the frequency of the wave
-
25%
b) zero frequency
-
0%
c)the frequency of the wave
-
25%
d)half the frequency of the wave
Q.10.
Which of the following can be expressed in coulomb
-
25%
a)
-
50%
b)
-
25%
c)
-
0%
d)
Q.11.
The sound waves after being converted into electrical waves are not transmitted as such because
-
0%
a) they travel with the speed of sound
-
50%
b) the height of antenna has to be increased several times
-
50%
c)they are heavily absorbed by the atmosphere
-
0%
d)frequency is not constant
Q.12.
Given the wave function ( in S.I. units) for a wave to be ψ(x, t)=103 x - 9×1014) t speed of the wave is
-
0%
a) 3×106 m/s
-
50%
b) 3 × 107 m/s
-
0%
c) 3 × 108 m/s
-
50%
d) 9 ×1014 m/s
Q.13.
If the electric amplitude of the wave is 5 V/m. The magnetic amplitude of this wave is
-
0%
a)5 AWb/m2
-
75%
b) 1.67 ×10-10 Wb/m2
-
25%
c)1.67 × 10-8 Wb / m2
-
0%
d)5.0 × 10-10 Wb / m2
Q.14.
Dimensions of following are
-
0%
a) potential
-
0%
b) charge
-
75%
c)current
-
25%
d)capacitance
Q.15.
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]
-
50%
a) 1015
-
25%
b) 1014
-
0%
c)1013
-
25%
d)1012
Q.16.
Radio wave of constant amplitude can be generated with
-
25%
a) Filter
-
25%
b) Rectifier
-
0%
c) FET
-
50%
d) OScillator
Q.17.
If Vg , Vx and Vm are the speeds of gamma rays, X-rays and microwaves respectively in vacuum then [ C.P.M.T. 1994]
-
0%
a)Vg < Vx < Vm
-
25%
b) Vg > Vx > Vm
-
50%
c)Vg > Vx < Vm
-
25%
d)Vg=Vx=Vm
Q.18.
The oscillating electric and magnetic field vectors of an electromagnetic waves are oriented along
-
50%
a) mutually perpendicular direction and are in pahse
-
25%
b) mutually perpendicular directions and differ in phase by 90°
-
25%
c)the same direction but different in pahse by 90°
-
0%
d)the same direction and are in phase
Q.19.
The wavelnegth of microwaves is [ AMU 1995]
-
25%
a) smaller than the wavelength of violet light
-
25%
b) smaller than the wavelnegth of yellow light
-
25%
c)larger than the wavelength of red light
-
25%
d)larger than the wavelength of radio waves
Q.20.
If µo be the permiability and ko, the dielectric constant of a medium, its refractive index is give by [ MNR 1995]
-
25%
a) 1 / (õoko)
-
0%
b) 1 / (µoko)
-
75%
c) õoko
-
0%
d) µoko
Q.21.
Microwaves are electromagnetic waves with frequency, in the range of [ C.E.T 1996]
-
0%
a)micro hertz
-
25%
b) mega hertz
-
50%
c)giga hertz
-
25%
d)hertz
Q.22.
An accelerated electron would produce [ CPMT 1996]
-
0%
a) α- rays
-
0%
b) γ-rays
-
0%
c)β-rays
-
100%
d)E.M. rays
Q.23.
The phase and orientation of magnetic vector associated with electromagnetic oscillations differ respectively from those of the corresponding electric vector by [ CET 1997]
-
0%
a) zero and zero
-
75%
b) zero and π/2
-
25%
c)π/2 and π/2
-
0%
d)π/2 and zero
Q.24.
If εo and µo represent the permittivity and permiability of vaccum and ε and µ represent the permitivity and permiability of medium, then refractive index of the medium is given by
-
0%
a)
-
67%
b)
-
33%
c)
-
0%
d)
Q.25.
An electromagnetic wave going through vaccum is described by E=Eo sin( kx - ω t ) and B=Bo Sin ( kx - ω t )
-
0%
a)EoBo=ωk
-
0%
b) Eoω=Bok
-
100%
c) Eok=Boω
-
0%
d)None of these
Q.26.
A flood light is covered with filter that transmits red light. The electric field of the emenerging beam is represented by a sinusoidal plane wave Ex=36sin(1.2 ×107z - 3.6×1015t) V/m. The average intenisty of beam in watt/ metre2 will be
-
25%
a) 6.88
-
25%
b) 3.44
-
50%
c)1.72
-
0%
d)0.86
Explanation
Q.27.
A parallel plate capacitor consists of two circular plates each of radius 12 cm and separarted by 5.0 mm. The capacitor is being charged by an external source. The charging current is constant and is equal to 0.15A. The rate of chage of potential difference between the plates will be
-
25%
a) 1.873×107 V/s
-
50%
b) 1.873×108 V/s
-
25%
c) 1.873×109 V/s
-
0%
d) 1.873×1010 V/s
Explanation
Q.28.
The sun delivers 103 W/m2 of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimensions 8m×20m will be
-
25%
a) 2.56 × 104 N
-
0%
b) 6.4 × 105 N
-
25%
c) 4.0× 105 N
-
50%
d) 1.6 × 105 N
Q.29.
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
-
25%
a)8.53×10-5 N
-
0%
b) 2.3×10-3 N
-
25%
c)1.33×10-3 N
-
50%
d)5.33×10-4 N
Q.30.
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
-
25%
a) 0.6 ×10-10
-
50%
b) 2.4 ×10-9
-
0%
c)3.6 ×10-8
-
25%
d)4.8×10-7