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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 5601. |
Consider the situtaion shown in figure. Find distance of image of O from eye E. |
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Answer» Solution :Shift by (1), `t_(1)(1-1//mu_(1))=3(1-2//3)=1cm` Shift by (2), `t_(2)(1-1//mu_(2))=4(1-4)=3cm` Shift by (3), `t_(3)(1-1//mu_(3))=6(1-1//3)=4 cm` IMAGE of O is formed at I. OI=8 cm `rArrEO=6+6+1+4+1+3+6=27 cm` EI=EO-OI=27-8=19 cm |
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| 5602. |
Which of the four resistances P,Q,R and S generate the greatest amount of heat when a current flows from A to B ? |
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Answer» Q |
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| 5603. |
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 )/(sqrt(2)) (d) sqrt(2)E |
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Answer» <P>`(E )/(2)` `THEREFORE P PROP E^(2)` `therefore (P_(2))/(P_(1))=((E_(2))/(E_(1)))^(2)` `(50)/(100)=((E_(2))/(E ))^(2)` `((1)/(2))^(1//2)=(E_(2))/(E )` `therefore E_(2)=(E )/(sqrt(2))` |
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| 5604. |
In the network shown, the connector of mass m, length l and negligible resistance can smoothly side along two fixed parallel rails. The capacitor is initially uncharged and ET a uniform magnetic field B exists in the region directed into the plane of paper. If the switch S is closed at t=0 then the charge on the capacitor after long time is |
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Answer» `(mcepsilon)/(2(B^2l^2c+m))` |
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| 5605. |
In telescope, ratio of resolving power due to light of lambda. = 4000Å and lambda = 6000Å is ...... |
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Answer» `4:5` `=(D)/(1.22 lambda)` D and 1.22 are constant. `:.` Resolution power `prop (1)/(lambda)` `:.` Ration `=(lambda_(2))/(lambda_(1))=(6000)/(4000)=(3)/(2)` |
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| 5606. |
Phase of SHM . |
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Answer» Solution :Phase of simple HARMONIC motion REPRESENT the state of oscillation of the particle peforming simple harmonic motion (SHM), i.e.,it gives the displacement of the particle and its directionof motion from the equlibriumposition. The displacement of a particle in SHM is given by ` x=A sin ( OMEGA t+ alpha)` . The angle `(omegat+alpha)` is called the phase angle or simply the phase of SHM. |
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| 5607. |
Statement-1: It takes more fuel for a spacecraft to travel from the earth to moon than for the return trip. Statement-2: Potential energy of spacecraft at moon's surface is greater than that at earth surface. |
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Answer» Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1. |
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| 5608. |
The velocity of particle is v=v_0 +gt+ft^(2) if its position is x =0 at t=0, then its displacement after unit time is: |
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Answer» `v_0 +g//2+f//3` or `(dx)/(dt)=v_0`+gt+`ft^(2)` `dx=v_0dt`+ gt dt+`ft^2` dt `int_(0)^(x) dx=v_(0)int_(0)^(1)dt+gin_(0)^(1)t dt +f int_(0)^(1) t^(2) dt` `=v_0 +(g)/(2)+(f)/(3)` |
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| 5609. |
The magnetic field at a distance at a distance 2 cm from a magnetic pole is 2 xx 10^(-4) tesla. The pole strength of the pole (in A - m) is |
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Answer» 8 |
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| 5610. |
Q amount of electric charge is present on thesurface of a sphere having radius R. Calculate the total energy of the system. |
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Answer» `(kQ^(2))/(R)` `:.` AVERAGE electric potential V `= (V_(0)+V_(Q))/(2) = (kQ)/(2R)` `:.` Potential energy `U = VQ = (kQ^(2))/(2R)` |
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| 5611. |
लीडिग कोशिकाओं का पाया जाना तथा उनसे निकलने वाले पदार्थ क्रमश: होते हैं: |
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Answer» अग्नाशय एंव ग्लुकेगॉन |
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| 5612. |
Consider sunlight incident on a pinhole of widht 10^(3)Å. The image of the pinhole seen on a screen shall be |
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Answer» a sharp white ring. `(lamda)/(d)=(6000)/(1000)=6implies(lamda)/(d)gtgtgtgt1` Amount of diffraction would be very large. HENCE image would appear different than geometrical image. Thus option (B) is correct. In the present case, at the central point on the screen, constituent colours of white light superpose with equal proportion and produce constructive interference to give white coloured spot at the central position. But as we MOVE away from centre, on the successive rings, constructive interference takes place for different colours (in the order from blue to red) and so different colours are dominant in different rings (with very small amounts for remaining colours). Thus, region around central white spot appears to be colourful in which as the order of MAXIMUM increases, intensity of light goes on decreasing. It means this region diffuses as we move away from centre. Thus, option (D) is also correct. |
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| 5613. |
Two capacitors of capacity 4 muF and 6 mu F are connected in series and a battery is connected to the combination. The energy stored is E_1 If they are connected in parallel and if the same battery is connected to this combination the energy stored is E_2The ratio E_1 :E_2 is |
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Answer» `4:9` |
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| 5614. |
A beaker of height H is made up of a material whose coefficient of linear thermal expansion is 3alpha. It is filled up to the brim by a liquid whose coefficient of volume expansion is 3alpha. If now the beaker along with its contents is uniformly heated through a small temperature T, the level of liquid will reduced by ("Given, " alphaT ltlt 1) |
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Answer» `alphaTH` |
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| 5615. |
Define magnetic field. |
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Answer» Solution :The magnetic field `VEC(B)` at a point is defined as a force e`xx`perienced by the bar magnet of unit pole strength. `vec(B) = (1)/(q_(m)) vec(F) ` Its unit is `N A^(-1) m^(-1)` |
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| 5616. |
Show that the force on each plate of a parallel plate capacitor has a magnitude equal to (½) QE, where Q is the charge on the capacitor, and E is the magnitude of electric Held between the plates. Explain the origin of the factor 1//2 |
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Answer» Solution :Let area of plate is A and surface charge DENSITY is `SIGMA` . Charge on capacitor q = `sigma`A and electric field `E= (sigma)/(in_(0))` The work done for increasing the distance `Delta`x between two plates of capacitor opposite to the force, W = `FDeltax ` If `rho_(E)` is the energy density of capacitor then potential energy of capacitor = density `xx` INCREASE in VOLUME `F.Deltax = rho_(E)xxA Deltax` `:. F = rho_(E) xxA ` `:. F = (1)/(2) in_(0) E^(2) A [ because rho_(E)= (2) in_(0)E^(2)]` `=(1)/(2) in_(0)ExxEA` `=(1)/(2) sigmaA xxE [because E = (sigma)/(in_(0))implies sigma = E in_(0)]` `:. F = (1)/(2) qE [ because sigma = (q)/(A) implies q = sigma A ]` The physical origin of the factor `(1)/(2)` in the force formula lies because just outside the conductor,field is E and inside it is zero. Hence, it is the average value `(E)/(2)` of the field that CONTRIBUTE to the force. |
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| 5617. |
1 ohm resistance is in series with an Ammeter which is balanced by 75cm of potentiometer wire. A standard cell of 1.02V is balanced by 50cm. The Ammeter shows a reading of 1.5A.The error in the Ammeter reading is |
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Answer» `0.002 A` |
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| 5618. |
Energy of a charged capacitor is U. Now it is. removed from the battery and then it is connected to another uncharged capacitor having the capacitance twice the first one In parallel. The energy of first and second capacitors respectively is ...... |
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Answer» `(1)/(9) U, (1)/(9)` U `U (Q^(2))/(2C)` `U_(1)=(((Q)/(3))^(2))/(2C)=(Q^(2))/(9xx2C)=(U)/(9)` `U_(2)=(((2Q)/(3))^(2))/(2xx2C)=(4Q^(2))/(9xx2xx2C) = (2U)/(9)` |
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| 5619. |
"The most incomprehensible thing about the world is that it is comprehensible." Who made these remarks? |
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Answer» Newton |
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| 5620. |
(a) How is an electromagnet different from a permanent magnet? (b) Write two properties of a material which make it suitable for making electromagnets. |
| Answer» SOLUTION :(b) A MATERIAL is SUITABLE for MAKING electromagnets if its relative permeability is high but retentivity and coercivity both are SMALL. | |
| 5621. |
A glass sphere (mu = 1.5) of radius 20cm has a small air bubble 4 cm below its centre. The sphere is viewed from outside and along a vertical line through the bubble. The apparent depth of the bubble below the surface of sphere is (in cm) |
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Answer» 13.33 |
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| 5622. |
Draw a labelled diagram of a moving coil galvanometer. Describe briefly its principle and working. |
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Answer» SOLUTION :PRINCIPLE and working : A current carrying coil, placed in a UNIFORM magnetic field, (can) experience a torque Consider a rectangular coil for which no. of turns `=` N, Area of cross-section `= l xx b = A`, Intensity of the uniform magnetic field `=B`, Current through the coil `= I` `:.` Deflecting torque `= B I l xx b = B I A` For N turns `tau =` NBIA Restoring torque in the spring `= k theta` ( `k=` restoring torque per unit twist) `:. N B I A = k theta` `:. I = ((k)/(NBA))theta` `:. I prop theta` The deflection of the coil, is therefore, PROPORTIONAL to the current flowing through it. 
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| 5623. |
The internal resistances of two cells shown are 0.1Omega and 0.3Omega. If R=0.2Omega, the potential difference across the |
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Answer» cell B will be zero and A will be less than 2V. |
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| 5624. |
Give some examples of paramagnetic substance. |
| Answer» SOLUTION :ALUMINIUM, SODIUM, Calcium, Oxygen (at STP) and Copper chloride | |
| 5625. |
A solid sphere of radius 'R' has a cavity of radius (R)/(2). The solid part has a uniform charge density 'rho' and cavity has no charge. Find the electric potential at point 'A'. Also find the electric field (only magnetude) at point 'C' inside the cavity |
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Answer» |
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| 5626. |
Short wave propagation of radio waves consists of freqeuncies which are reflected by ionosphere. Some important technical terms are defined related to the free electron density N of layers and the frequencies v to be reflected are mentioned in Column-I. They are related to frequency v and free electron density N as shown in Column-II |
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Answer» A - 1 , B -2 , C - 3 , D - 4 |
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| 5627. |
For making standard resistance, wire of following materials is used |
| Answer» Answer :D | |
| 5628. |
Which of the following statement is correct about the scalar quantity ? |
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Answer» A SCALAR quantity is always conserved in a process. |
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| 5629. |
In the word of Hyugens "Light propagates aslongitudinal waves" comment on the abovestatement. |
| Answer» SOLUTION :LIGHT WAVES can not be longitudinal as it EXHIBIT POLARISATION. | |
| 5630. |
In the figure shown an infinitely long wire carries a current I_(1) and another uniform rigid wire ACB (bent at C at right angle) of mass m carries a current I_(2).It is hinged at corner C.Find the angular acceleration of this wire ACB just after release.Is the direction of rotation clockwise or anticlockwise.(Assume gravity is absent) [Take ln^(2)=~0.7] |
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Answer» `dtau=(DF).(2L-x)` in clockwise sense. `dF=(I_(2)dx)mu_(0)/(2pi) I_(1)/x` `therefore` Net torqeu on wire `AC` about `C` is `tau_(1)UNDERSET(L)overset(2L)int(mu_(0))/(2pi)(I_(1)I_(2)(2L-x))/xdx=(mu_(0))/(2pi)I_(1)I_(2)L(ln 4-1)` `=(0.4mu_(0)I_(1)I_(2)L)/(2pi)`(clockwise direction) Magnetic field at each point on segment `BC` due to infinite wire is uniform. `therefore` Net torque or wire `BC` about `C` is `tau_(2)=(mu_(0)/(2pi)I_(1)/(2L))I_(2) LxxL/2=mu_(0)/(8pi)I_(1)I_(2)L`(anticlockwise direction) `because tau_(1) gt tau_(2) rArr "net torque" tau=tau_(1)-tau_(2)=mu_(0)/(8pi)(0.6)I_(1)I_(2)L`(clockwise direction) moment of inertia of `L` shaped rod about `C` is `I=(mL^(2))/3` angular ACCELERATION `alpha=tau/I=(0.6mu_(0)I_(1)I_(2)L)/(8pi)xx3/(mL^(2))=(9mu_(0)I_(1)I_(2))/(40pimL)` 
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| 5631. |
The half-life of a radioactive substance is 100 years, Calculate in how many years the activity will decay to 1/10th of its initial value. |
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Answer» 332.3 years |
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| 5632. |
The equation of two progressive waves are y^1 = 8sin(200pit - x/8 + pi) and y^2 = 6 sin( 200pit -x/8) cm. if two waves superpose at a point , the resultant amplitude is |
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Answer» 14 CM. |
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| 5633. |
A : Light added to light can produce darkness. R : The destructive interference of two coherent light sources may give dark fringe. |
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Answer» Both A and R are TRUE and R is the CORRECT explanation of A |
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| 5634. |
An images of bright square is obtained on a screen with the aid of a convergent lens. The distance between the square and the lens is 40 cm. The area of the image is nine larger than that of the square. Select the correct statement(s): |
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Answer» image is formed at a distance of 120 cm from lens |
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| 5635. |
Two charges 4q and q are fixed at points (0,9) and (12, 0) respectively on the X-Y plane. Find the coordinates of the point where the electric field strength is zero. |
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Answer» |
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| 5636. |
Three unequal resistor in parallel are equivalent to a resistance 1Omega If two of them are in the ratio 1:2and if no resistance value is fractional the largest of the three resistance in ohm is |
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Answer» 4 |
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| 5637. |
According to Einstein's photo electric equation , the graph between the K.E. of photo electrons ejected and the frequency of incident radiation is |
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Answer»
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| 5638. |
A man standing in a lift holds a spring balance with a load of 5 kg suspended from it. What would be the reading of the balance when the lift is descending with an acceleration of 4ms^(-2) ? |
| Answer» Answer :C | |
| 5640. |
Statement - I: The absorbtance of a perfact black body is unity. Statement - II : A perfect black body when heated emits radiations of all possible wavelength at that temperature. |
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Answer» Statement - I is true, Statement - II is true and Statement - I is correct explanation for Statement - II. So correct CHOICE is (B). |
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| 5641. |
The electric field due to an electric dipole. At large distance ® from it, falls of as ___________ |
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Answer» |
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| 5642. |
A capacitor of capacitance 8 muF is connected across a 200 V power supply. The energy gained by the capacitor is ___________ . |
| Answer» Solution :`0.16 J, u = 1/2 CV^2= 1/2 xx (8 xx 10^(-6)) xx (200)^2 =0.16J` | |
| 5643. |
Using Bohr's postulates, obtain the expressions for (i) kinetic energy and (ii) potential energy of the electron in stationary state of hydrogen atom. Draw the energy level diagram showing how the transitions between energy levels result in the appearance of Lymann Series. |
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Answer» Solution :This series is produced when ELECTRON jumps from higher orbits to the first STATIONARY orbit (i.e., `n_(F) =1`).Thus, for this series. `bar(v) =(1)/(lambda)=R((1)/(l^(2)) -(1)/(n_(i)^(2)))` `therefore " where"n_(i)=2, 3, 4, 5...` For the longest wavelength of Lyman Series `n_(i)=2.` 
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| 5644. |
Coercivity of a magnet where the ferromagnet gets completely demagnetized is 3 xx 10^(3) A m^(-1), The minimum current required to be passed in a solenoid having 1000 turns per metre, so that the magnet gets completely demagnetized when placed inside the solenoid is |
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Answer» 3A |
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| 5645. |
A narrow beam of thermal neutrons passes through a plate of iron whose absorption and scattering effective cross-sections are equal to sigma_(a)= 2.5 b and sigma_(s)=11 b respectively. Find the fraction of neutrons quitting the beam due to scattering if the thickness of the plate is d= 0.50 cm. |
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Answer» Solution :In traversing a distance `d` the fraction which is either SCATTERED or absorbed is clearly `1-e^(-n(sigma_(s)+sigma_(a))d)` by the usual definition of the attenuation factor. Of this, the fraction scattered is (by defination of scattering and ABSORPTION cross SECTION) `w={1-e^(-n(sigma_(s)+sigma_(a))d)} (sigma_(s))/(sigma_(s)+sigma_(a))` In iron `n=(rhoxxN_(A))/(M)=8.3xx10^(22)per c c` Substitution GIVES `w=0.352` |
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| 5646. |
Ozone layer blocks the radiations of wave length |
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Answer» LESS than`3XX10^(-7)` m |
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| 5647. |
A polaroid (I) is placed in front ofmonochromatic source. Another polaroid(II) is placed in front of this polaroid (I) and rotated till no light passes. A third polaroid(III) is now placed in between (I) and (II). In this case, will light emerge from (II)? Explain. |
| Answer» Solution :(i) Only in the special cases when the pass axis of (III) is parallel to (I) or (II) there shall be no light EMERGING. (ii) In all other cases there shall be light emerging because the pass axis of (II) is no LONGER perpendicular to the pass axis of (III). | |
| 5648. |
(A) : The microwaves are better carriers of signals than radio waves. (R) : The electromagnetic waves do not require any medium for propagation. |
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Answer» Both 'A' and 'R' are true and 'R' is the CORRECT EXPLANATION of 'A'. |
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| 5649. |
Stae how the Balmer Series of spectral lines are generated ? |
| Answer» Solution :The BALMAR series CONSISTS of all those wavelengths which are limited when electron JUMPS at orbit `n = 2 ,1/lambda = R(1/n_1^2 - 1/n_2^2)`. | |
| 5650. |
A ball dropped from a point P crosses a point Q in t seconds. The time taken by it to travel from Q to R, if PQ = QR. |
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Answer» `t` |
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