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Recent questions in Class12
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JEEMAIN and NEET
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Physics
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Class12
Class12
Electric Charges and Fields
Electrostatic Potential and Capacitance
Current Electricity
Moving Charges and Magentism
Magnetism and Matter
Electromagnetic Induction
Alternating Current
Electromagnetic Waves
Ray Optics and Optical Instruments
Wave Optics
Dual Nature of Matter and Radiation
Atoms
Nucleii
Semiconductor Materials and Electronic Devices
Communication Systems
Experimental Skills in Physics
The conduction band of a solid is partially filled at OK.Then the solid is
jeemain
physics
class12
unit19
ch14
q15
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
Electrical conductivity of pure germanium can be increased by 1) increasing the temperature 2) doping with donor impurities 3) radiation with ultra violet rays. 4) doping with acceptor impurities
jeemain
physics
class12
unit19
ch14
q14
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
In a p-n junction the depletion region is $200 nm$ wide and a electric field of $10^6 vm^{-1}$ exists in it. What is the minimum kinetic energy of conducting electron to diffuse through the barriers.
jeemain
physics
class12
unit19
ch14
q13
medium
pn-junction
semiconductor-electronics
asked
Jan 27, 2014
by
meena.p
1
answer
In pure semiconductor number of conducting electrons is $5 \times 10^{20} $ per cubic meter. How many holes are there in $1 cm^3$ of the same semiconductor.
jeemain
physics
class12
unit19
ch14
q12
medium
intrinsic-and-extrinsic-semiconductor
semiconductor-electronics
asked
Jan 27, 2014
by
meena.p
1
answer
The impurity atom with which pure silicon can be doped to make p-type semiconductors are
jeemain
physics
class12
unit19
ch14
q11
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
What is intensity of electric field in the depletion region of which $2.5 \times 10^{-7} m$ if the potential barrier is $0.50 v$
jeemain
physics
class12
unit16
ch14
q10
easy
intrinsic-and-extrinsic-semiconductor
semiconductor-electronics
asked
Jan 27, 2014
by
meena.p
1
answer
A p type semiconductor has acceptor level of 50 mev above the valance band. Find the maximum wave length of light which can create a hole.
jeemain
physics
class12
unit19
ch14
q9
easy
intrinsic-and-extrinsic-semiconductor
semiconductor-electronics
asked
Jan 27, 2014
by
meena.p
1
answer
The diffusion current in p-n junction is due to
jeemain
physics
class12
unit19
ch14
q8
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
Electronic conduction to in a semiconductor takes place due to
jeemain
physics
class12
unit19
ch14
q7
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
Which of the following are incorrect statements about a transistor?
jeemain
physics
class12
unit19
ch14
q6
medium
concepts
semiconductor-electronics
pn-junction
transistors
asked
Jan 27, 2014
by
meena.p
1
answer
The reverse bias in p-n junction
jeemain
physics
class12
unit19
ch14
q5
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
In p-n junction diode : the depletion zone has
jeemain
physics
class12
unit19
ch14
q4
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
Semi conductors doped with donor atoms have majority carriers as
jeemain
physics
class12
unit19
ch14
q3
easy
semiconductor-electronics
concepts
asked
Jan 27, 2014
by
meena.p
1
answer
Fermi energy is
jeemain
physics
class12
unit19
ch14
q2
easy
concepts
semiconductor-electronics
asked
Jan 27, 2014
by
meena.p
1
answer
Which of the following is true about semiconductors?
jeemain
physics
class12
ch14
semiconductor-electronics
concepts
easy
asked
Jan 27, 2014
by
meena.p
1
answer
A plate of thickness x made of refractive index $\mu $ is placed in front of one of the slits in a double slit experiment. What should be minimum thickness x . so that the central maxima turns to fringe with minimum intensity
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
difficult
asked
Jan 24, 2014
by
meena.p
1
answer
Equi convex lens is placed such that optic axis coincides with the x-axis, position of object is $(-40 \;cm, 1 \;cm) $ and position of image $(50 \;cm, -2\;cm) $ where is the lens located
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
refraction-at-spherical-surfaces-and-lenses
difficult
asked
Jan 24, 2014
by
meena.p
1
answer
A ray of light is incident on a prism of refractive index $\mu =\sqrt 2$ It is found that the deviation caused is $30^{\circ}$ The angle of prism is $60^{\circ}$ What will be the angle between the ray inside the prism and the base of the prism .
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
refraction-by-prism
difficult
asked
Jan 24, 2014
by
meena.p
1
answer
A prism of refractive index $\mu =1.5 $ of vertical angle $6 ^{\circ}$ is placed in front of a mirror. A ray of light is incident normally on one of the face of the prism as shown. What is the total deviation caused by the system.
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
refraction-by-prism
difficult
asked
Jan 24, 2014
by
meena.p
1
answer
Two waves have a phase difference of $\pi $. and they have light intensities I and 9I. What will be the resultant intensity .
jeemain
physics
class12
unit16
wave-optics
addition-of-waves
medium
asked
Jan 24, 2014
by
meena.p
1
answer
Find the width of central maxima given $\lambda = 5 \times 10^{-5}\;cm$ slit separation $d= 0.15 \;cm$ and distance between screen and slit $D= 2.1 \;m$
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
medium
asked
Jan 24, 2014
by
meena.p
1
answer
An unpolarised light is incident on a glass plate at polarizing angle $57^{\circ}$ with the normal on a glass plane. The reflected light will be
jeemain
physics
class12
unit16
wave-optics
polarisation
medium
asked
Jan 24, 2014
by
meena.p
1
answer
In Young's double slit experiment the distance between adjacent fringe is x and L is distance between slit and screen. If d is split separation , then wave length is
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
easy
asked
Jan 24, 2014
by
meena.p
1
answer
An interference pattern is observed in a young 's double slit experiment in air. Now this chamber is evacuated and the same light is used we will see .
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
easy
asked
Jan 24, 2014
by
meena.p
1
answer
Wave nature of light explains the phenomenon of
jeemain
physics
class12
unit16
wave-optics
introduction-to-wave-optics
easy
asked
Jan 24, 2014
by
meena.p
1
answer
A ray of light passes through four transparent media with refractive indices $\mu_1, \mu_2, \mu_3$ and $\mu_4$ as shown. The surface of all media are parallel. The emerging say CD is parallel to incident ray AB, Then ,
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
refraction
difficult
asked
Jan 24, 2014
by
meena.p
1
answer
In Lloyd's single mirror experiment A light wave emitted directly from sources s interferes with a wave reflected from a mirror M. The interference pattern is formed on the screen which is kept perpendicular to the mirror and at a distance. $D=1 m$ from the source as shown . If the sources is at a distance of 1 mm from the plane of the mirror what is the fringe width when monochromatic light of 600 nm is incident from the sources
jeemain
physics
class12
unit16
wave-optics
interference
difficult
asked
Jan 24, 2014
by
meena.p
1
answer
In a young's double slit experiment illuminated by monochromatic light the slit separation is $0.3\;mm$ and slit- screen separation is $1.5 \;m$. If fourth bright fringe is 1 cm from central bright fringe, the wavelength of light used is
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
medium
asked
Jan 24, 2014
by
meena.p
1
answer
In a young's double slit experiment the fringe width is $0.05\;mm$ when the distance of screen from slit is $75 \;cm$ . If the distance of screen from the slit is increased by $25 \;cm$ , the fringe width will be
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
medium
asked
Jan 23, 2014
by
meena.p
1
answer
A slit of width 'a' is illuminated by white light. For what value of 'a' will the first minimum for red light of wavelength $\lambda =650 \;nm$ appear for $\theta =30^{\circ}$?
jeemain
physics
class12
unit16
wave-optics
diffraction
medium
asked
Jan 23, 2014
by
meena.p
1
answer
What is the angular separation between two lines of $\lambda_1 =5882 \mathring{A}$ and $\lambda_2 =5852 \mathring{A}$ in first order grating with 6000 lines per cm in normal incidence.
jeemain
physics
class12
unit16
wave-optics
diffraction
medium
asked
Jan 23, 2014
by
meena.p
1
answer
A thin film of oil of $\mu =1.2 $ floats on watch of $\mu_w =\large\frac{4}{3}$. A monochromatic light of wave length $\lambda= 9600 A^{\circ} $ falls normally and it appears dark. What must be minimum change in thickness of oil film which will appear bright if normally reflected by same light.
jeemain
physics
class12
unit16
wave-optics
interference
difficult
asked
Jan 23, 2014
by
meena.p
1
answer
A Plastic film of thickness t is placed in the path of one of the interfering wave in the young's double slit experiment and it is found that the central fringe is displaced through a width of 5 fringes . If wavelength of light used is $5890 \mathring{A}$ What is thickness of film used
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
medium
asked
Jan 23, 2014
by
meena.p
1
answer
Two waves from coherent sources $S_1$ and $S_2$ having wavelength $\lambda$ arrive at a point P and complete destructive interference takes place . The path difference between them is
jeemain
physics
class12
unit16
wave-optics
coherent-sources-addition-of-waves
easy
asked
Jan 23, 2014
by
meena.p
1
answer
Two slit in a young's double slit experiment is separated by a distance d. The screen distance is D and it is illuminated by a light of wavelength $\lambda$. A point 0 on the screen is $\large\frac{2d}{3} $ distance from the point which is directly in front of one of the slits. How far away is 0 from the central bright fringe.
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
easy
asked
Jan 23, 2014
by
meena.p
1
answer
Two coherent sources of light $S_1 $ and $S_2$ are placed in a line as shown. Two screens are placed perpendicular to $S_1S_2$ at A and B . It is observed that at point P a bright fringe is seen , then at point Q.
jeemain
physics
class12
unit16
wave-optics
coherent-sources-addition-of-waves
medium
asked
Jan 23, 2014
by
meena.p
1
answer
In a Young's double slit experiment at a point P on the screen the light from two slit with a path difference of $\large\frac{\lambda}{6} $ Where $\lambda$ is the wavelength of the incident light . The intensity of light at point P is I. If $I_0$ is maximum intensity then $\large\frac{I}{I_0}$
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
easy
asked
Jan 23, 2014
by
meena.p
1
answer
In a young's double slit experiment 'd' distance between slit is $0.5\; mm$ and illuminated by light of $\lambda =6000 A^{\circ}$ If screen distance is 2.5m ,thedistance of third bright fringe from centre.
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
easy
asked
Jan 23, 2014
by
meena.p
1
answer
In a Young's double slit experiment light of $\lambda =5000\mathring{A}$ is incident on two slits. At a point P on the screen the two rays arriving have a path difference of $1 \times 10^{-6} \;m$. If the central fringe (zero) is maxima . What is formed at p.
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
medium
asked
Jan 23, 2014
by
meena.p
1
answer
Maximum intensity of the interference pattern in a young double slit experiment is I. Distance between slit is $d= 5 \lambda$ where $\lambda $ is wave length of the light source. What will be the intensity of light at a point directly in front of one of the slits. $(D= 50 \lambda)$
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
medium
asked
Jan 23, 2014
by
meena.p
1
answer
In a Young's double slit experiment 'd' distance between slit is $1 \times 10^{-4}\;m$ and $D=1\; m $. ( distance of screen from slits ) At a point P on the screen the resulting intensity is equal to the intensity due to individual slit $I_0$ The distance of P from central maxima when wavelength of $x=6000\;\mathring{A}$ is
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
difficult
asked
Jan 23, 2014
by
meena.p
1
answer
A polariser and an analyser are oriented so that maximum light is transmitted of intensity $I_0$ What will be the intensity of the out coming light when analyer is rotated through $60^{\circ}$
jeemain
physics
class12
unit16
wave-optics
polarisation
easy
asked
Jan 23, 2014
by
meena.p
1
answer
In a single slit experiment a wave of wavelength $0.2 \;cm$ is incident normally on a slit of width $0.004\;m$ . What is the semi angular width of the central maxima.
jeemain
physics
class12
unit16
wave-optics
diffraction
easy
asked
Jan 23, 2014
by
meena.p
1
answer
The first diffraction minima due to a single diffraction is at $30^{\circ}$ for a light of wave length $5000A^{\circ}$ the width of slit is
jeemain
physics
class12
unit16
wave-optics
diffraction
medium
asked
Jan 23, 2014
by
meena.p
1
answer
The maximum distance a person having defect of short right can see clearly is 4 meters. The power of lens required to correct is
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
optical-instruments
easy
asked
Jan 23, 2014
by
meena.p
1
answer
In Young's double slit experiment if width of slit is made 3 folds, the fringe width becomes
jeemain
physics
class12
unit16
wave-optics
youngs-double-slit-experiment
easy
asked
Jan 23, 2014
by
meena.p
1
answer
The contrast in the dark and bright fringes in any interference pattern depends on
jeemain
physics
class12
unit16
wave-optics
addition-of-waves
easy
asked
Jan 23, 2014
by
meena.p
1
answer
A double convex lens $(\mu =1.5) $ has its focal length 10 cm. What will be its focal length if it is immersed in liquid of $(\mu_1=\large\frac{4}{3})$
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
refraction-at-spherical-surfaces-and-lenses
medium
asked
Jan 23, 2014
by
meena.p
1
answer
The objective of a telescope has a diameter 5 cm. What is the angular seperation in radius of two starts which can be resolved by the telescope when light of $3000 A^{\circ}$ is used.
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
optical-instruments
medium
asked
Jan 23, 2014
by
meena.p
1
answer
The magnifying power of telescope is 9. when it is adjusted for parallel rays, the distance between objective and eye piece is found to be 20 cm. The focal length of lenses are
jeemain
physics
class12
unit16
ray-optics-and-optical-instruments
optical-instruments
medium
asked
Jan 23, 2014
by
meena.p
1
answer
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