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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.
| 40251. |
The speed (v) of ripples on the surface of waterdepends on surface tension (sigma), density (rho) and wavelength (lambda). The square of speed (v) is proportional to |
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Answer» `sqrt((GAMMA)/(rho))` |
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| 40252. |
A block has been placed on an inclined plane. The slope angle of the plane is such that the block slides down the plane at a constant speed. The coefficient of kinetic friction is equal to |
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Answer» `sin THETA` |
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| 40253. |
(A): The positively charged nucleus of an atom has a radius of almost 10^(-15)m (R): In a-particle scattering experiment, the distance of closest approach for aparticles isa - particles is 10^(-15)m |
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Answer» Both .A. and .R. are TRUE and .R. is the CORRECT EXPLANATION of .A. |
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| 40254. |
Which part of electromagnetic spectrum is absorbed from sunligh by ozone layer? |
| Answer» SOLUTION :ULTRAVIOLET RAYS | |
| 40255. |
What is the (a) momentum, (b) speed, and (c) de Broglie wavelength of an electron with kinetic energy of 120 eV. |
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Answer» SOLUTION :(a) `5.92xx10^(-24)kgms^(-1)` (b) `6.50xx10^(6)ms^(-1)` (C) 0.112nm |
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| 40256. |
A cyclotron's oscillating frequency is 5 MHz i. What should be the operating magnetic field for accelerating deutrons? iiWhat is the kinetic energy of the deutrons if the radius of the dees is 56 cm? Mass of deutrons = 3.3 xx 10^(-27)kg. Charge of deutron = 1.6 xx 10^(-19) C |
| Answer» Solution :i.0.65 TII. `5.11 xx 10^(-13) J ` | |
| 40257. |
In Young's double-slit experiment,, monochromatic light of wavelength 630 nm illuminates the pair of slits and produces an interference pattern in which two consecutive bright fringes are separated by 8.1mm. Another source of monochromatic light produces the interference pattern in which the two consecutive bright fringes are separated by7.2 mm. find the wavelength of light from the second source. What is the effect on the interference fringes if the monochromatic source is replaced by a source of white light ? |
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Answer» SOLUTION :Here for `lamda_(1)=630nm`, the fringe width `beta_(1)=8.1mm`. If for light of wavelength `lamda_(2)` the fringe width be `beta_(2)=7.2mm`, then `(beta_(2))/(beta_(1))=(lamda_(2))/(lamda_(1))implieslamda_(2)=(beta_(2)lamda_(1))/(beta_(1))=(7.2mm)/(8.1mm)xx630nm=560nm`. for EFFECT on the INTERFERENCE fringe PATTERN when a monochromatic source is replaced by a source of white light. |
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| 40258. |
A beam of light consisting of two wavelengths, 650 nm and 520 nm,is used to obtained interference friges ina Young's double slit experiment. a. Find the distance of the third bright fringe on the screen from the central maximum for wavelength 650 nm. |
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Answer» Solution :a. `lamda=650xx10^(-9)m, d=2XX10^(-3)m, D=1.2mm, n=3` `:.y_(3)=(n lamda D)/d=(3xx650xx10^(-9)xx1.2)/(2xx10^(-3))=1.17xx10^(-3)m` `BETA=(D lamda)/d=(y_(n))/n=(1.17xx10^(-3))/3=0.39xx10^(-3)m` b. `(nDlamda_(1))/d=((n+1)Dlamda_(2))/d` (higher order of lower WAVELENGTH COINCIDES with lower order of higher wavelength) `n lamda_(1)=(n+1)lamda_(2), n/(n+1)= (lamda_(2))/(lamda_(1))=520/650=0.8` `n=0.8n+0.8, 2n=0.8 :. n=4` `y_(n)^(.)=(n D lamda_(1))/d=n beta=4xx0.39xx10^(-3)=1.56xx10^(-3)m` |
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| 40259. |
A block of mass M is placed on a smooth table. Its two sides are attached to fixed walls by means of collinear horizontal springs of spring constants k_(1) and k_(2)(k_(1)gt k_(2)) as shown in the Figure. The block is made to oscillate horizontally along the line of the two springs. The frequency of its oscillation is : |
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Answer» `(1)/(2PI)((k_(1)+k_(2))/(M))^((1)/(2))` |
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| 40260. |
If the magnetic dipolemomentof an atom of dimagnetic material paramagnetic material and ferromagnetic material are denoted by mu_(d)mu_(p) and mu_(f) respectively then |
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Answer» `mu_(d)=0` NAD `mu_(p) ne0` |
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| 40261. |
In a single reflection from the ionosphere, the sky waves cover a distance on ground not more than |
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Answer» 400m |
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| 40262. |
Figure is the plot of the stopping potential versus the frequency of the light used in an experiment on photoelectric effect. Find (a) the ratio h/e and (b) the work function. |
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Answer» Solution :We have to take two cases Case - I`v_0 = 1.656 ``v = 5 XX 10^(14) Hz` Case -II ` v_0 = 0 ` ` v = 1 xx 10^(14) Hz` (b) We know ` ev_0 = hv - W_0 ` ` 1.656 e =H xx 5 xx 10^(14) - W_0 ` `0 = 5h xx 10^(14) - 5W_0 ` ` 1.6556 e = 4W_0` ` rArr W_0 = 1.656 / 4 eV ` ` = 0.414eV ` (a) Putting the VALUE of W_0 in equation (2) ` rArr 5 W_0 = 5h xx 10^(14) ` `rArr 5 xx 0.414= 5 xx h xx 10^(14)` ` rArr h = 4.414 xx 10^(-15) eV-s` |
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| 40263. |
Two plates of a parallel plate capacitor carry charges q and -q and are separated by a distance a from each other. The capacitor is connected to a constant voltage source V_0. The distance between the plates is changed to x+dx. Then in steady state. |
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Answer» change in electrostatic energy stored in the CAPACITOR is `-UDX//x` . INITIAL stored energy `U_(i)=(1)/(2)(epsilon_(0)AV_(1)^(2))/(x)` Final stored energy `U_(f)=(1)/(2)(epsilon_(0)AV_(0)^(2))/(2(x+dx))` So `DeltaU=U_(f)-U_(i)=(1)/(2)epsilon_(0)AV_(0)^(2)[(1)/(x+dx)(1)/(x)]` `=(1)/(2)epsilon_(0)AV_(0)^(2)[(x-x-dx)/(x(x+dx))]` `=(1)/(2)(epsilon_(0)AV_(0)^(2))/(x^(2))dx=(1)/(2)(epsilon_(0)AV_(0)^(2))/(x)(edx)/(x)=-(Udx)/(x)` So, option (a) is correct and option (b) is incorrect. `F=(dU)/(dx)=(-(V)/(x))` `=(1)/(2)(epsilon_(0)A)/(x)(V_(0)^(2))/(x)=(-(1)/(2))((epsilon_(0)A)/(x)V_(0)) (V_(0))/(x)=-(1)/(2)qE` So magnitude of attractive force is `1//2qE`. So, option (c) is correct and option (d) is incorrect |
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| 40264. |
Which of the following systems are digital? |
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Answer» Clinical the mometer |
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| 40265. |
A man in a balloon rising vertically with an acceleration of 4.9 ms releases a ball 2 second after the balloon is let go from the ground. The greatest height above the ground reached by the ball is: |
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Answer» 14.7 m `v=u+at=0+4.9xx2=9.8 ms^(-1)` and height atttained by ballon in first 2 `SEC =(1)/(2) at^(2)` `:.` Total height GAINED by ball =9.8+4.9=14.7m |
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| 40266. |
What is the total +ve charges in Coulombs of all the protons in 1 mole of hydrogen atoms ? |
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Answer» Solution :CHARGES of each atoms e= ` 1.6x10^(-19) C` Number of atoms in ` 1 "MOLE" =6.022 xx 10 ^(23) ` ` because ` TOTAL charges ` = 6.022 xx 10^(22) xx 1.6 xx 10 ^(-19) =6.93 xx 10 ^(4) C ` |
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| 40267. |
Someof the equipotential surfaces of the magnetic scalar potential the magnitude of magnetic field B at a point in the region is |
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Answer» `10^(-3) T` Now `B=(DV)/(dr)` Even for `theta=120^(@)`the magnitude of fieldis same |
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| 40268. |
A thin conducting spherical shell of radius R has a charge Q which is uniformly distributed on its surface . The correct plot for electroistatic potential due to this spherical shell is ………… . |
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Answer»
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| 40269. |
For two vectors vec(a) and vec(b),|vec(a) + vec(b)|=|vec(a)-vec(b)| when |
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Answer» `|a|=|b|ne0` `|vec(a)+vec(b)|=sqrt(a^(2)+b^(2)2abcostheta)` and `|vec(a)-vec(b)|=sqrt(a^(2)+b^(2)-2abcostheta)` When `theta=90^@,costheta=0` and `|vec(A)+vec(b)|=|vec(a)-vec(b)|` |
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| 40270. |
Who came to Mini's home while she was feeding Mitra ? |
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Answer» Postman |
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| 40271. |
Television (T.V.) is areceiver that can be tuned to any transmitter. We can therefore, watch and enjoy the T.V. programms of our choice on different channels at prescribed times. Read the above passage and answer the following questions: (i) Why do children feel that T.V. is a boon ? (ii) What are the reservations of elderly people with regard to television? (iii) What are your personal views on the subject? |
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Answer» Solution :(i) For children, T.V. is a boon, because it is a source of knowledge, information and LOT of entertainment. (ii) Elderly people have reservations about the T.V. because all sorts of PROGRAMMES including Audit channels, fashion channels, horror shows, etc. are telecast. They feel that children are immature and their minds get impregnated with wrong values. The television consumes a lot of time, disconnects them from society and LEAVES little time for their studies. (iii) Personally, I feel we have to strike a balance between the views of children and the views of elderly people. Too much of everything is bad and children must be guided to view educative programes (e.g. on DISCOVERY channel, National geographic channel, etc.), News channels, Comedy programmes for a limited time of 1-2 hours a day. This will MAKE them more knowledgbale and also save their precious time for studies. |
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| 40272. |
Coils P and Q each have a large number of turns of insulated wire. When switch S is closed, the pointer of galvanometer G is deflected toward the left (as shown in the following figure). With Snow closed, to make the pointer of G deflect toward the right one could |
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Answer» Move the SLIDE of the rheostat R QUICKLY to the right |
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| 40273. |
A mass 'M' is suspended by a rope from a rigid support. It is pulled horizontally with a force F. If the rope makes an angle 'o' with vertical in equilibrium, then the tention in the string is |
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Answer» `F SIN THETA` |
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| 40274. |
The magnetising field required to be applied in opposite direction to reduce residual magnetism to zero is called |
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Answer» retentivity |
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| 40275. |
In an experiment for calibration of voltmeter, a standard cell of emf 1.5V is balanced at 300cm length of potentiometer wire. The P.D.across a resistance in the circuit is balancedat 1.25m.If a voltmeter is connected across the same resistance, it reads 0.65V.The errorin the volt meter is |
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Answer» `0.05V` |
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| 40276. |
In a carnival ride, the passenger travels in a circle of radius 5 m making one complete circle in 4 sec. What is the acceleration |
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Answer» `24.6 m/s^2` |
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| 40277. |
A : The peculiar fish Anableps anableps swims with its eyes partially extending above the water surface so that it can see simultaneously above and below water. R : This fish has egg shaped eye lens and two retina. |
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Answer» If both Assertion & Reason are TRUE and the reason is the correct explanation of the assertion, then MARK (1). |
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| 40278. |
An ac generator is ued to convert mechanical energy.But what dose a transformer do? What are different types of transformer? |
| Answer» SOLUTION :A transformer transformrs electrical power at low VOLTAGE into electrial power at HIGH voltage and VICE -verss step up transformer and step down transformer are the two TYPES of transformers. | |
| 40279. |
A 10 kg satellite circles earth once every 2 h in an orbit having a radius of 8000 km. Assuming that Bohr’s angular momentum postulate applies to satellites just as it does to an electron in the hydrogen atom, find the quantum number of the orbit of the satellite. |
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Answer» Solution :From EQ., we have `mv_n r_n = nh//2pi` Here m = 10 kg and `r_n = 8 xx 10^6 m`. We have the time period T of the circling SATELLITE as 2 h. That is `T = 7200 s`. THUS the velocity `v_n = 2pi r_n//T`. The quantum number of the orbit of satellite `N = (2pi r_n)^2 xx m//(T xx h)`. Substituting the values, `n = (2pi xx 8 xx 10^6 m)2 × 10//(7200 s xx 6.64 xx 10^(-34) J s)` `= 5.3 xx 10^(45)`. |
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| 40280. |
One mole of an ideal monoatomic gas is taken through a polytropic process P^2T = constant. The heat required to increase the temperature of the gas by DeltaT is |
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Answer» `R DELTAT` |
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| 40281. |
Six point charges are placed at the vertices of a regular hexagon of side a as shown. If E represents electric field and V represents electric potential at O then, |
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Answer» E = 0 but V `ne` 0 |
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| 40282. |
A whistle producing sound waves of frequencies 9500 Hz and is approaching a stationary person with speed v ms^(-1) The velocity of sound in air is 300 ms^(-1). If the person can hear frequencies upto a maximum of 10,000 Hz. The maximum value of v upto which he can hear the whistle is |
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Answer» `30 MS^(-1)` |
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| 40283. |
When an electrons makes a transition from higher orbit in the hydrogen atom, what are the lines of the Balmer series obtained ? |
| Answer» SOLUTION :Second | |
| 40284. |
The angle between the vectors vec(A) and vec(B) is theta. The value of triple Product vec(A).vec(B)xxvec(A) is : |
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Answer» `A^(2)Bcostheta` `:. Vec(A).(vec(B)xxvec(A))=0` |
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| 40285. |
A thin uniform rod (mass= 0.90kg) swings about an axis that passes through one end of the rod and is perpendicular to the plane of the swing. The rod swings with a period of 1.5s and an angular amplitude of 10^(@). (a) What is the length of the rod? (b) What is the maximum kinetic energy of the rod as it swings? |
| Answer» SOLUTION :(a) 0.84m, (B) 0.056J | |
| 40286. |
There are two planets. The ratio of radius of the two planets is K, but ratio of acceleration due to gravity of both planets is g. What will be the ratio of their escape velocity? |
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Answer» `(Kg)^(1//2)` Since escape velocity `V=sqrt(2gR)` `therefore (v_(1))/(v_(2))=sqrt((g_(1))/(g_(2)).(R_(1))/(R_(1)))=sqrt(GK)=(Kg)^(1//2)` Thus correct CHOICE is (a). |
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| 40287. |
Shows the electric field lines around three point charges A,B and C. (a) Which charges are positive ? (b) Which charge has the largest magnitude? Why?(##U_LIK_SP_PHY_XII_C01_E09_005_Q01.png" width="80%"> |
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Answer» Solution :(a) CHARGES A and C are positive but charges B is negative. (b)The charges C has LARGEST magnitude because maximum number of electric field lines are ORIGINATING from it. |
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| 40288. |
If volume of Earth is V and area of Earth is A, then its capacitance will be ...... |
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Answer» `4 PI epsilon (A)/(V)` Volume ` V = (4)/(3) pi R^(3)` and area A `= 4 pi R^(2)` `:. (V)/(A) = (4//3pi R^(3) )/(4pi R^(2)) = (R)/(3)` `:. R = (3V)/(A)` `:. C = 4pi in_(0)xx(3V)/(A)` `:. C = 12 pi in_(0)(V)/(A)` |
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| 40289. |
which of thefollowingcomplexes entitiesaresqure planarin shape ? {:([Ni(CN)_(4)]^(-2)[MnCl_(4)]^(-2)[Zn(NH_(3))_(4)]^(+2)),(" "(P) ""(Q)""(R )):} {:([PdCl_(4)]^(-2)[Ni(NH_(3))_(4)]^(+2)),(" "(S)""(T)):} |
Answer» Solution :
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| 40290. |
A pure inductor of 25.0 mH is connected to a source of 220 V . Find the inductive reactance and rms current in the circuit if the frequency of the source is 50 Hz. |
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Answer» Solution :Magnitude of inductive reactance is, `X_(L) = omega L ` `= 2 pi F L` `= ( 2) ( 3.14 ) ( 50) ( 25 xx 10^(-3))` ` = 7.85 Omega` Here, `V_(RMS) = I_(rms) X_(L)` `:. I_(rms) = ( V_(rms)/ X_(L))` `= ( 220)/( 7.85)` `= 28.025 A` |
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| 40291. |
(A): When conducting loop is kept stationary in a non-uniform magnetic field an emf is induced. (R): As per Faraday's law, whenever flux changes, an emf is induced. |
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Answer» Both A and R are TRUE and R is the CORRECT explanation |
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| 40292. |
A point charge Q is surrounded by two concentric spherical surfaces of radii R and 2R, respectively. A point charge is at the common centre. If f_1 and f_2 be the total electric flux over surfaces (1) and (2), then f_1//f_2 will be |
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Answer» `1:2` |
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| 40293. |
What do you mean by dispersion of light ? |
| Answer» Solution :The phenomenon of which a composite LIGHT splits up into its constituent COLOURS is known as DISPERSION of light . | |
| 40294. |
Two satellites A and B revolve round a planet in coplanar orbits in the same direction their periods are 1 hour and 8 hours respectively. The orbital radius of A is 10^(4) km the speed of B relative to A when they are closet is : |
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Answer» `10^(4)pi` km/h |
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| 40295. |
Solar rays are incident at 45^(@) on the surface of water (mu=4//3). The length of the shadow of a pole of length 1.2 m formed at the bottom of the pond is 3.3/n where n is (if the poleis vertical assuming that 0.2 m of the pole is above the water surface) |
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Answer» 40 |
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| 40296. |
Four conectric conducting shells A, B,C,D are of radii a, 2a, 3a, 4a respectively. B and D carry charges + Q and -Q where A & C are neutra. Now the shell .C. is earthed. |
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Answer» Charge appearing on .C. after earthing is `(Q)/(4)` |
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| 40297. |
(a) An X-ray tube produces a continuous spectrum of radiation with its short wavelength end at 0.45 Å. What is the maximum energy of a photon in the radiation? (b) From your answer to (a), guess what order of accelerating voltage (for electrons) is required in such a tube ? |
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Answer» SOLUTION :(a) 27.6 KEV (B) of the ORDER of 30 kV |
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| 40298. |
The diameter of the objective of a telescope is doubled. In what ratio will the intensity of image increase? |
| Answer» Solution :On doubling the diameter, the AREA of the objective will become FOUR times the original value. Therefore, the amount of light ENTERING the telescope will ALSO become four times. CONSEQUENTLY, the intensity of the image will increase four times. | |
| 40299. |
(a) Givethree reasons whymodulation of a messagesignal is necessaryfor longdistancetransmission. (b)Showgraphically an audio singal, a carrier waveandan amplitude modulation wave. |
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Answer» Solution :THREE regions are following: (i)Modulation ALLOWS US to senda singalovera bandpass frequecnyrange. (ii) To allowthe useof a smallerantenna. (III) In ratio COMMUNICATION, modulation is needed in the transmission system to transfer the messageinto the availablehigh freqeuncy radio channel. 
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| 40300. |
A charge of IC is placed at one end of a non conducting rod of length 0.6m . The rod is rotated in a vertical plane about a horizontal axis passing through the other end of the rod with angular frequency 10^(4)pi"rad"/s. Find the magnetic field at a point on the axis of rotation at a distance of 0.8 m from the centre of the path |
| Answer» SOLUTION :`B=(mu_(0)ir^(2))/(2(r^(2)+X^(2))^(3//2)),i=(qomega)/(2pi)rArrB=(mu_(0))/(4pi)(qomegar^(2))/((r^(2)+x^(2))^(3//2))` | |
