WorksheetsEMI & AC , EM Waves, Ray Optics, Wave Optics
Total questions: 50
Worksheet time: 23mins
Electro motive force induced by motion of conductor across magnetic field is called
EMF
motional EMF
rotational EMF
static EMF
Square coil of side 16 cm having 200 turns rotating in magnetic field of 0.05 T with peak EMF of 12 V will produce angular velocity of
47 rad s-1
49 rad s-1
42 rad s-1
48 rad s-1
Self-induced EMF is sometimes also known as
induced EMF
deduce EMF
back EMF
both a and b
A moving conductor coil produces an induced e.m.f. This is in accordance with :
Lenz’s law
Faraday’s law
Coulomb’s law
Ampere’s law
A device that transforms mechanical energy to electrical energy is a
generator
motor
transformer
magnet
What happens to the galvanometer if the copper rod is moved upwards?
No change
Deflect to the right
Deflect to the left
Deflect to the right and left
A pure inductor is connected to an AC power supply. In this circuit, the current
leads the voltage by 90°.
lags the voltage by 90°.
is in phase with the voltage.
none of the given answers.
If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor
increases to 4 times its original value.
increases to twice its original value.
decreases to one-half its original value.
decreases to one-fourth its original value.
What happens at resonance?
Current is maximum
Impedance is maximum
Resistance is maximum
Power factor is maximum
The instantaneous current in an ac circuit is i=2.0 sin314t, what is rms value of the current.
1.414 A
2.828A
1 A
2 A
The instantaneous current in an ac circuit is i=2.0 sin314t, what is rms value of the current.
1.414 A
2.828A
1 A
2 A
What is alternating current
the process of inducing an emf (voltage) with a change in magnetic flux
Electric currents whose direction and magnitude change periodically depending on time are called alternating current
Steady current which delivers the same average power as the a.c. to a resistive load.
Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor
A changing magnetic field B induces an emf Ɛ in a coil of radius R, as shown figure. What is the induced emf in the coil of radius 2R?
Ɛ
2 Ɛ
4 Ɛ
Ɛ/2
Ɛ/4
The Phase Angle between Current and Voltage in a Resistance circuit is
0
2−π
4π
+2π
Rotating Vectors are called as
Rotating Vectors
Phasors
Tensors
There is no such Vector
The Phase angle between Current and Voltage in a LCR circuit is given by
arctan (XL - XC / R)
tan (XL - XC/R)
arctan (XC- XL/R)
tan (XC - XL/R)
Which of the following is not electromagnetic waves
UV rays
Gamma rays
β rays
X-rays
To which part of the spectrum does EM waves belong if the energy of the wave is of the order of 15 KeV
X rays
Infrared rays
Ultraviolet rays
Gamma rays
The magnetic field in a travelling electromagnetic wave has a peak value of 20nT. The peak value of electric field strength
3 V/m
6 V/m
9 V/m
12 V/m
Maxwell’s equations describe the fundamental laws of
Electricity only
Magnetism only
Mechanics only
Both (A) and (B)
The penetrating power of X-ray increases with the increases in its
velocity
intensity
frequency
wavelength
A radiowave has a maximum magnetic field induction of 10-4 T on arrival at a receiving antenna . The maximum electric field intensity of such a wave is
zero
3× 104 V/m
5.8× 10-9 V/m
3.3× 10-13 V/m
Who was the first to give a practical demonstration of the production of e.m, wave
J.C. bose
Marconi
Maxwell
Hertz.
Consider an extended object immersed in water contained in a plane trough. When seen from close to the edge of the trough the object looks distorted. Which of the following is not correct.
The apparent depth of the points close to the edge are nearer the surface of the water compared to the points away from the edge.
The angle subtended by the image of the object at the eye is smaller than the actual angle subtended by the object in air.
Some of the points of the object far away from the edge may not be visible because of total internal reflection.
Water in a trough acts as a lens and magnifies the object.
Critical angle and refractive index are:
Directly related
Equal
Inversely related
None of these
For a total internal reflection, which of the following is correct?
Light travels from rarer to denser medium.
Light travels from denser to rarer medium.
Light travels in air only.
Light travels in water only.
A prism has refracting angle of 600 . When a ray is incident at 500 on one face, it suffers minimum deviation δm . The value of δm is
450
600
550
400
A biconvex lens of equal radius of curvature R for each refracting surface, is placed at a point P in the path of a beam converging to a point M, such that PM = R/3. If the refractive index of the material of lens is 1.5, the magnification produced by the lens is
3/4
-3/4
4/3
1
If the tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting, calculate the focal length of the objective in cm
100
10
2
25
A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. the power of the combination is : ______
- 1.5 D
-6.5 D
+ 6.5 D
+ 6,67 D
If a plane wavefront is incident on a concave mirror, then the emergent wavefront will be _________ of the mirror as its centre.
conical with focus
spherical with focus
spherical with centre of the curvature of the surface
conical with centre of the curvature of the surface
According to Huygens principle of secondary wavelets, each particle at a wave front
is an electron
behaves as a photon
represents the direction of the motion of wave front
behaves as a new light source
What type of interference is represented in this diagram?
Constructive
Destructive
When a compression interferes with another compression, what occurs?
They counteract and the wave stops.
They combine to create a larger compression.
They combine to create a rarefaction.
None of the above.
For constructive interference to take place between two monochromatic light waves of wavelength λ the path difference should be
(2n -1 ) λ /4
(2n-1 ) λ /2
n λ
(2n +1) λ/2
Soap bubble appears coloured due to the phenomenon of
Interference
Diffraction
Dispersion
Reflection
What is the path difference of destructive interference
n λ
n (λ +1)
(n+1) λ /2
(2n+1 ) λ /2
The fringe width in YDS expt on a screen which is placed at a distance of 1m from the slits 10-3m apart when light used has wavelength 6 X 10-7 m , is equal to :
3 X 10-10 m
3 X 10-4 m
6 X 10-10 m
6 X 10-4 m
If the ratio of amplitudes of two interfering waves is 4 : 3 , then the ratio of maximum and minimum intensity is :
16 : 18
18 : 16
49 : 1
94 : 1
Light of wavelength 2 X 10-3 m falls on a slit of width 4 X 10-3 m. The angular dispersion of the central maximum will be :
300
600
900
1800
We combine two lenses, one is convex and other is concave having focal lengths /, and f2 and their combined focal length is F. Combination of the lenses will behave like concave lens, if
f1 > f2
f1 = f2
f1 < f2.
f1 ≤ f2
The focal length of a biconvex lens of radii of each surface 50 cm and refractive index 1.5, is
40.4 cm
75 cm
50 cm
80 cm
A convex lens of refractive index 3/2 has a power of 2.5 D in air. If it is placed in a liquid of refractive index 2 then the new power of the lens is
– 1.25 D
– 1.5 D
1.25 D
1.5 D
The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4. Which of the four rays correctly shows the direction of reflected ray?
1
2
3
4
_______ principle says that each point of the wavefront is the source of a secondary disturbance and the wavelets emanating from these points spread out in all directions with the speed of the wave.
Rayleigh
Maxwell
Huygens
Hertz
EM waves used in checking the authenticity of bank notes
microwave
infrared
ultraviolet
X-ray
The focal length of a converging lens are fV and fR for
violet and red light respectively. Then
fV > f R
fV = f R
fV < f R
any of the three is possible depending on the value of
the average refractive index m
an air bubble inside water behaves as
converging lens
Diverging lens
Rainbow is an example of which phenomenon?
(a) Refraction and scattering
(b) Refraction and total internal reflection
(c) Dispersion and reflection
(d) Dispersion and total internal reflection
A
B
C
D
What happens to the refractive index on heating the liquid?(a) Increases
(b) Decreases
(c) Remains unchanged
(d) Increases or decreases depending on the rate of heating
A
B
C
D
