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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A string of mass per unit length .mu , is clamped at both ends. Such that one end of the string is at x = 0 and the other is at x = l. When string vibrates in fundamental mode amplitude of the mid-point O of the string is a, and tension in the string is T. The total oscillation energy stored in the string is: (pi^(2)a^(2)T)/(Nl). Then N |
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| 2. |
Number of points where the function f(x)={{:(max(|x^2-x-2|","x^2-3x)","ifx ge0),(max(log(-x)","e^x)"," if x lt 0)):} isnon-differentiable , is |
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Answer» 1 
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| 3. |
A charged particle is moving in a circular path under the action of the Lorentz force. How much work is done by the force in one revolution? |
| Answer» Solution :Zero, because FORCE is ACTING PERPENDICULAR to the direction of motion of the charged particle. | |
| 4. |
Two block of masses 3 kg and 1 kg are kept in contact with rach other on a frictionless horizontal surface. If a force of 10 N is applied on the larger block what is the acceleration of the system? What is the contact force between the two blocks? |
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Answer» `2.5 m//s^(2)` , 2.5 N |
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| 5. |
(A) : The values of in and μ depend on the medium. (R) : The electromagnetic force between two charges or magnets depends on the medium in which they are located. |
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Answer» Both 'A' and 'R' are true and 'R' is the correct EXPLANATION of 'A'. |
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| 6. |
If a photon of energy E has velocity c and frequency v, then which of following represents its wavelength |
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Answer» `(HC)/(E)` |
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| 7. |
A sinusoidal plane wave falls on a partially rigid boundary of reflection coefficient 0.36 Consider the location of the boundary at x = 0. Let the equation of incident wave be y! = a sin (cot - kx). Then: |
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| 8. |
Which one is NOT a vector? |
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Answer» Displacement |
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| 9. |
(I) : In some AC generators, converts electrical energy into mechanical energy. (II) : A Transformer converts high voltage (low current) into low voltage (high current ) and vice versa. Which one is incorrect statement ? |
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| 10. |
If a spoke is connected between the rim of the wheel and the centre (axlc) and B_(mu) is the earth 's horizontal component of total field perpendicular to the plane of the wheel and the wheel is rotated with an angular speed, then what will be the induced emf between the ends of the spoke ? |
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Answer» Solution :Induced EMF `=1/2 BomegaR_2`. Note : Induced emf .E. `=Bd/(dt)` (area of a SECTOR swept by the between the two POINTS on the rim). i.e., `e=Bd/(dt)((R_2)/2theta)=1/2BR^2(d""theta)/(dt)=1/2BR^2omega` |
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| 11. |
Equal volumes of copper and mercury have the same thermal capacity. Sp. heat of mercury is 0.046" cal/gm/"^(@)C and density is 13.6 g/c.c. What is the density of copper if its specific heat is 0.090 ? |
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Answer» `0.695 g//cc` or `V xx 13.6 xx0.046 =V xx d xx 0.09` `THEREFORE d =(13.6xx0.046)/(0.09)=6.95` g/c.c. `therefore` Correct CHOICE is (b). |
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| 12. |
In figure the direct image formed by the lens (f = 10 cm) of an object placed at O and that formed after reflection from the spherical mirror are formed at the same point 'O'. Whatis the radius of curvature of the mirror? |
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Answer» Solution :v= 15 CM. f = 10 cm ` 1/15 - 1/U = 1/10 ` or u = - 30 cm DISTANCE of O from the mirror = 20 cm. |
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| 14. |
Two point objects, separated by a distance of 6 xx 10^(-5) cm, are to be resolevd using a microscope. Calculate the numerical aperture if light of wavelength 546 nm is used. |
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| 15. |
The energy of an electron in hydrogen atom is -3.4 eV, then itsangular momentum is ...... |
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Answer» `2.1xx10^(-34)JS` `:.-3.4=-(13.6)/(n^(2))` `:.n^(2)=(13.6)/(3.4)=4` `:.n=2` `:.` ANGULAR momentum in `n^(th)` ORBIT, `L_(n)=(nh)/(2pi),n=2` `L_(2)=(2h)/(2pi)=(h)/(PI)=(6.625xx10^(-34))/(3.14)=2.109xx10^(-34)` `:.L_(2)~~2.5xx10^(-34)Js` |
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| 16. |
On which of the following scales of temperature the temperature is never negative |
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Answer» a)Celsius |
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| 17. |
Which of the following gives a correct correspondence between electrical and mechanical quantities ? |
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Answer» CURRENT `to` VELOCITY |
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| 18. |
The balancing lengths of potentiometer wire are 800 cm and 600cm when two cells of emf's E_(1) and E_(2) are connected in the secondary circuit first in series and then terminals of one cell is reversed,E_(1)/E_(2)is equal to |
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Answer» `1//11` |
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| 19. |
निम्नलिखित समुच्चयों को रोस्टर रूप में लिखिए A = {x : X, एक पूर्णांक है और -3 |
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Answer» A={-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7} |
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| 20. |
Answer the questions : Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around sauall obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the justification ? |
| Answer» SOLUTION :Typical sizes of APERTURES INVOLVED in ORDINARY optical instruments are much larger than. the WAVELENGTH. | |
| 21. |
If the material particle is moving with velocity v and the velocity of light is c, then mass of particle is taken as (m_0 is rest mass) |
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Answer» `m=m_0/c` |
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| 22. |
A constant horizontal force vec(F)_(a) pushes a 2.00 kg package across a frictionless floor on which an xy coordinate system has been drawn. Figure 5-42 gives the package's x and y velocity components versus time t. What are the (a) magnitude and (b) direction of vec(F)_(a ? |
| Answer» SOLUTION :(a) `11.7N,` (B) `-59.0^(@)` | |
| 23. |
A bulb of 800 W electrical power has efficiency 6%. It is kept at the centre of a sphere of diameter 20 cm. If surface of this sphere is a perfect reflector then find force exerted on it. |
| Answer» SOLUTION :`F=32xx10^(-8)N` | |
| 24. |
What is the size and consitution of the nucleus? |
| Answer» Solution :The SIZE of the nucleus is much SMALLER than that of ATOM the size of the nucleus is 10,000 TIME smaller than the size of the atom .But more than `99.9%` of the whole massis concentrated at the nucleus it consists of protons and NEUTRONS . | |
| 25. |
A molecule of a substance has permanent dipole moment p. A mole of this substance is polarised by applying a strong electrostatic field E. The direction of the field is suddenly changed by an angle of 60^(@). If N is the Avogadro's nwnber the amount of work done by the field is ...... |
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Answer» <P>2 NpE For N mole : W = N p E ( 1- cos `theta`) `:. W = NP E 9 1 - cos 60^(@)]` ` :. W = NpE [ 1 -(1)/(2)]` `:. W = NpExx(1)/(2)` `:. W = (1)/(2) ` N pE |
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| 26. |
A balloon is going upwards with a velocity of 20 mIt releases a packet when it is at a height of 160 m from the ground. The time taken by the packet to reach the ground is |
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Answer» 6 s |
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| 27. |
At absolute zero temperature, a crystal of pure Germanium |
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Answer» BEHAVES as a PERFECT conductor |
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| 28. |
Statement-1: Two rigid, identical and uniformly charged non conducting spheres with same charge are placed on a sufficiently rough surface, then spheres must be in equilibrium. Statement-2: If net force on a point charge is zero it is in equilibrium. |
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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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| 29. |
The vibrations of a string of length 60 cm fixed at both ends are represented by the equation. y=4 sin [(pi x)/(15)] cos(96 pi t) where x and y are in cm and t in sec. (a) What is the maximum displacement al r = 5 cm? (b) What are the nodes located along the string ? (c) What is the velocity of the particle at x=7.5 and t=0.25 s ? (d) Write down the equations of component waves whose superposition gives the above wave. |
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Answer» maximum displacement of a particle at a POINT at x = t cm is 4 cm |
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| 30. |
A call is connected across 250 V, 50 Hz supply and it draws a current of 2.5 A and consumes power of 400 W. Find the self inductance and power factor. Data : E_(rms) = 250 V, v = 50 Hz, I_(rms) = 2.5 A, P = 400 W, L = ?, cos phi = ? |
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Answer» Solution :Power `P = R_(rms)I_(rms) COS phi` `:. Cos phi = (P)/(E_(rms)I_(rms))` `= (400)/(250 xx 2.5)` `cos phi = 0.64` Impedance `Z = (E_(rms))/(I_(rms)) = (250)/(2.5) = 100 OMEGA` also,`sin phi = (X_(L))/(Z)` `:. X_(L) = Z. sin phi = Z SQRT(1- cos^(2) phi)` `=100 sqrt(1- (0.64)^(2)]` `:. X_(L) = 76.8 Omega` But `X_(L) = L omega= L2pi V` `:. L = (X_(L))/(2pi v) = (76.8)/(2pi xx 50)` `:. L = 0.244 H` |
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| 31. |
Energy of characteristic X-ray is a consequence of |
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Answer» a) energy of PROJECTILE electron |
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| 32. |
A cylinderal tank has a hole of 1.6cm^(2) in its bottom. If the water is allowed to flow into the tank from a tube above it at the rate of 80 cm^(3)//s, then the maximum height up to which water can water can rise in the tank is |
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Answer» 0.25cm |
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| 33. |
In a Young.s double slit experiment wave length of light used is 5000 A and distance between the slits is 2mm, distance from slits is 1m. Find fringe width and also calculate the distance of 7^(th) dark fringe from central birght fringe. |
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Answer» Solution :Given = ` lamda = 5000 xx 10^(-10) m = 5 xx 10^(-7) m` d = ` 2 xx 10^(-3) m , D = 1m ` We knowthat ,fringewidth` BETA = ( lamdaD)/d ` i.e, ` beta = ( 5 xx 10^(-7)xx1 )/( 2 xx 10^(-3)) = 2.5 xx 10^(-4) m ` i.e,`beta = 2.5 xx 10^(-4) m` The distanceof darkfringe ` x_(4) = ((2n+1)beta)/2 ` i.e, Distanceof ` 7^(TH) `darkfringe = ` ((2xx6+1)/2) ( 2.5 xx 10^(-4)) ` n = ` 1.625 xx 10^(-3) m` Hencedistanceof ` 7^(th)` dark fringe = 1.625 mm. |
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| 34. |
Who was the first to predict the deflection of light rays by the gravitational field? |
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Answer» Einstein |
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| 35. |
Two discs A and B are mounted coaxially on a vertical axle. The discs have moments of inertia I and 2I respectively about the common axis. Disc A is imparted an initial angular velocity 2omega using the entire potential energy of a spring compressed by a distance x_(1). Disc B is imparted an angular velocity omega by a spring having the same spring constant and compressed by a distance x_(2). Both teh discs rotate in the clockwise direction. The ratio (x_(1))/(x_(2)) is : |
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Answer» 2 `therefore (1)/(2)I(2omega)^(2)=(1)/(2)kx_(1)^(2)` and `(1)/(2)xx2Iomega^(2)=(1)/(2)kx_(2)^(2)` DIVIDING `(x_(1)^(2))/(x_(2)^(2))=2and(x_(1))/(x_(2))=sqrt(2)` |
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| 36. |
A battery is connected between two points A and B on the circumference of a uniform conducting ring of radius r and r |
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| 37. |
The mixture of a pure liquid and a solution in a along vertical column (i.e., horizontal dimensions lt lt vertical dimensions) produces diffusion of solute particles and hence a refractive index gradient along the vertical dimension. A ray of light entering the column at right angles to the vertical is deviated from its original path. Find the deviation in travelling a horizontal distance d lt lt h, the height of the column. |
Answer»  By snell's law, `mu(y)sin theta = mu(y+dy) sin (theta+d theta)` `[mu(y)+(dmu)/(dy)dy] (sin theta cos d theta+ cos theta sin d theta)` As `d theta` is small, `cos d theta ~~ 1` and `sind theta ~~ d theta`. `:. mu(y) cos theta = (dmu)/(dy)dysin theta, d theta= (-1)/(mu) (d mu dy tantheta)/(dy)` `[tan theta= (dx)/(dy)` and REPLACING `mu(y)` by `mu`] `theta = - 1/mu (d mu)/(dy)overset(d)underset(o)(INT)dx = - (1)/(mu)((dmu)/(dy)) d`. |
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| 38. |
For the same angle of incidence, the angles of refraction in three different media A, B and C are 15°, 25° and 35°, respectively. In which medium will the velocity of light be minimum ? |
| Answer» SOLUTION : In MEDIUM A in which ANGLE of REFRACTION is MINIMUM. | |
| 39. |
The distance between two points differeing in phase by 60^(@) on a wave having 360 |
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Answer» 0.72 m `thereforelambda = (u)/(v) = (360)/(500) = (18)/(25) ` m `x = (lambda)/(2pi).phi (18)/(25). (PI //3)/(2pi ) = 0.12 `m Hence CORRECT choice is (c). |
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| 40. |
(A) : A charged particle is moving in a circle with constant speed in uniform magnetic field. If we increase the speed of particle to twice, its acceleration will become four times. (R) : In circular path with constant speed, acce-leration is given v^(2)/R. If speed is doubled centripetal acceleration will become four times. |
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Answer» Both 'A' and 'R' are TRUE and 'R' is the CORRECT EXPLANATION of 'A'. |
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| 41. |
The figure shows a diagonal symetric arrangement of capacitors and a battery.The potential of the point B and D are |
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Answer» `V_B =8V` |
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| 42. |
In the circuit shown, r=4Omega, C=2muF (a) Find the current coming out of the battery just after the switch is closed. (b) Find charge on each capacitor in the steady state condition. |
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Answer» Solution :`(a)` Due to symmetry the points of equalpotential are joined together, and the circuit MAY be reduced as `R_(13)=(r )/(2)+(r )/(4)+(r )/(4)+(r )/(2)=(3)/(2)r` Here, `r=4Omega`, `R_(13)=(3)/(2)(4)=6Omega` Thus, `I=(24)/(R_(13))=(24)/(6)=4A`  `(b)` In the steady-state condition, the circuit may be reduced as `R_(13)=2r=2(4)Omega=8Omega` `I=(24)/(8)=3A` `V_(56)=(2r)(I)/(2)=Ir=(3)(4)=12V` Equivalent CAPACITANCE between `5` and `6` is `C_(56)=(C )/(2)=1muF` `:. q_(56)=C_(56)V_(56)=12muC` Now, `V_(97)=V_(17)-V_(19)= -r(I)/(2)+2(rI)/(2)=(rI)/(2)=((4)(3))/(2)=6V` `:. q_(97)=CV_(97)=(2)(6)=12muC` Similarly, `q_(89)=12muC` 
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| 43. |
Answer the following : (a) Name the em waves which are suitable for radar system used in aircraft navigation. Write the range of frequencey of these waves. (b) If the earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain. (c) An em waves exerts pressure on the surface on which it is incident. Justify. |
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Answer» Solution :(a) Microwaves are suitable for radar systems used in aircraft navigation. The range of frequency for these waves is 109Hz to 1012Hz. (b) In the ABSENCE of atmosphere, there would be no greenhouse effect on the surface of the EARTH. As a result, the temperature of the Earth would decrease rapidly, making it difficult for human survival. (c) An em wave carries a LINEAR momentum with it. The linear momentum carried by a protion of wave having energy U is GIVEN by p = Uc. Thus, if the wave incident on a material surface is completely absorbed, it delivers energy U and momentum p = Uc to the surface. If the wave is totally reflected, the momentum delivered is p = 2Uc because the momentum of the wave changes from p to -p . Therefore, if follows that an em waves incident on a surface exert a force and HENCE a pressure on the surface. |
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| 44. |
What is the use of an erecting lens in a terrestrial telescope? |
| Answer» SOLUTION :A terrstrial telescope has an ADDITIONAL erecting lens to MAKE the final IMAGE ERECT. | |
| 45. |
What is the magnetic potentail at a point 1 m away from the centre of a shrot magnetic dipole having magnetic moment 50 Am^2 along a line inclined to dipole axis at 60^@ |
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Answer» 5.2 `XX 10^-6` J/Am |
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| 46. |
The focal length of a convex lens of refractive index 1.5 is f when it is placed in air. When it is immersed in a liquid it behaves as a converging lens and its focal length becoms xf(x gt1). The refractive index of the liquid is |
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Answer» `gt3//2` |
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| 47. |
A spaceship of rest length 270 m races past a timing station at aspeed of 0.600c. (a) What is the length of the spaceship as measured by the timing station? (b) What time interval will the station clock record between the passage of the front and back ends of the ship? |
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| 48. |
When two soap bubbles coalesce to form a single bubble then its radius will be- |
| Answer» ANSWER :D | |
| 49. |
In the first order thermal decomposition of C_2H_5I(g) to C_2H_4 (g) + HI(g), the reactant in the beginning exerts a pressure of 2 bar in a closed vessel at 600 K. IF the partial pressure of the reactant is 0.1 bar after 100 minutes at the same temperature the rate constant in min^-1 is (log 2=0.3010) |
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Answer» `6.0 TIMES 10^-4` at t=0 2BAR 0 0 After 1000 MINUTES `0.1 (2-0.1) (2-0.1) =1.9 =1.9 Since, the reaction in first order. `k=2.303/t log""p/(p_0-x)` `k=2.303/1000 log""2/(2-1.9)` `=2.303/1000log 20` `k=3 times 10^-3 min^-1` |
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