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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 d.c main supply of e.m.f 220 V is connected across a storage battery of e.m.f 200 V through a resistance of 1 Omega . The battery terminals are connected to an external resistance R. The minimum value of R so that a current passes through the battery to charge it is: |
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Answer» Zero |
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| 2. |
A convex lens of focal length 15 cm is placed in front of a plane mirror at a distance 25 cm from the mirror. Whereon the optical axis and from the centre of the lens should a small object be placed such that the final imagecoincides with the object ? |
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Answer» 15 CM and on the opposite SIDE of the MIRROR |
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| 3. |
The decay constant for the radioactive isotope ""^(57)Co" is "3 xx 10^(-8) s^(-1). The number of disintegrations taking place in a milligram of pure ""^(57)Co per second is : |
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Answer» `10^(16)` Acitivity `=lambdaN` `=3 xx 10^(-8) xx (6.022 xx 10^(23) xx 10^(-3))/(57)` `=3.16 x 10^(11)` |
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| 4. |
A large fake cookie sliding on a horizontal surface is attached to one end of a horizontal spring with spring constant k=360 N/m, the other end of the spring is fixed in place. The cookie has a kinetic energy of 20.0 J as it passes through the spring's equilibrium position. As the cookie slides, a frictional force of magnitude 10.0 N acts on it . (a) How far will the cookie slide from the equilibrium position before coming momentarily to rest ? (c) What will be the kinetic energy of the cookie as it slides back through the equilibrium position ? |
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Answer» |
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| 5. |
A thin biconvex lens is prepared from glass of refractive index mu_2 = 3/2 . The two convex surfaceshave equal radii of 20 cm each. One of the surfaces is silvered from outside to make it reflecting. It is placed in a medium of refractive index mu_1 = 5/3.It acts as a |
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Answer» Converging MIRROR |
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| 6. |
Which of the following statements are correct about a planet revolving around Sun ? |
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Answer» Mechanical ENERGY of a planet is negative |
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| 8. |
A narrow beam of light is incident on a glass plate of refractive index 1.6. It makes an angle 53^@ with normal to the interface. Find the lateral shift of the beam at the point of emergence, if thickness of the plate is 30 mm. (Take sin53^@ = 0.8.) |
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Answer» 9.023 mm `n_1sintheta_1=n_2sin theta_2` (1) `sin53^@=1.6sintheta_2` 0.7986=1.6`sintheta_2` `thereforesin theta_2=(0.7986)/(1.6)=0.4991 ~~0.5 " rad "=30^@` Now, LATERAL shift, `x=(TSIN(theta_1-theta_2))/(costheta_2)` `=(30sin(53^@-30^@))/(COS30^@)=(30sin23^@)/(cos30^@)` `=(30xx0.3907)/(0.866)=13.53` mm |
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| 9. |
Radioactive elements whose nuclei are unstable and atoms of such elements emit alpha-particles or beta-particles along with the gamma-rays. Due to emission of alpha-particles or beta-particles, atomic number and atomic mass are changed. We cannot speed up or slow down this process by any physical or chemical change. It means we cannot affect radioactivity by changing temperature or pressure. Radioactivity is a spontaneous process of nuclear disintegration. Lead is heaviest stable atom. In fact all radioactive elements are finally converted into lead. Complete the reaction ""_(1)H^(1) + ""_(7)N^(15) to ............... + ""_(2)He^(4) |
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Answer» `""_(6)C^(12)` |
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| 10. |
Radioactive elements whose nuclei are unstable and atoms of such elements emit alpha-particles or beta-particles along with the gamma-rays. Due to emission of alpha-particles or beta-particles, atomic number and atomic mass are changed. We cannot speed up or slow down this process by any physical or chemical change. It means we cannot affect radioactivity by changing temperature or pressure. Radioactivity is a spontaneous process of nuclear disintegration. Lead is heaviest stableatom. In fact all radioactive elements are finally converted into lead. During a decay, |
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Answer» mass number remains unaffected and atomic number INCREASES by 2 |
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| 11. |
Radioactive elements whose nuclei are unstable and atoms of such elements emit alpha-particles or beta-particles along with the gamma-rays. Due to emission of alpha-particles or beta-particles, atomic number and atomic mass are changed. We cannot speed up or slow down this process by any physical or chemical change. It means we cannot affect radioactivity by changing temperature or pressure. Radioactivity is a spontaneous process of nuclear disintegration. Lead is heaviest stable atom. In fact all radioactive elements are finally converted into lead. The particle P emitted in the reaction is ""_(Z)X^(A) to ""_(z-1)Y^(A) +P + v |
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Answer» `BETA^(-1)` PARTICLES |
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| 12. |
The theoretical values for the rupture strength obtained in the previous problem exceed by tens of times the rupture strength of good steels and by many thousands of times the rupture strength of real ionic crystals. What is the explanation for this? |
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Answer» |
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| 13. |
Two batteries with e.m.f. 12 V and 13 V are connected in parallel across a load resistor ol 10 Omega . The internal resistances of the two batteries are 1 Omega and 2 Omega respectively. Tine voltage across the load lies between |
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Answer» `11.6 V and 11.7 V ` `E_(1) = 12 V, r_(1) = 1 Omega , R = 10 Omega` `E_(2) = 13 V, r_(2) = 2 Omega`, `I = ((E_(2))/(r_(1)) + (E_(2))/(r_(2)) )/(1 + (R)/(r_(1)) + (R)/(r_(2)))= ((12)/(5) + (13)/(2))/(1 + (10)/(1) + (10)/(2))` `therefore I = (12 + 6 - 5)/(1 + 10 + 5) = (18 - 5)/(16)` `therefore I = 1.156 ` A `therefore V = IR ` = `1.156 xx 10` `= 11.56 ` V ` therefore ` THUS it is between V = 11.5 V and V = 11.6 V |
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| 14. |
Radioactive elements whose nuclei are unstable and atoms of such elements emit alpha-particles or beta-particles along with the gamma-rays. Due to emission of alpha-particles or beta-particles, atomic number and atomic mass are changed. We cannot speed up or slow down this process by any physical or chemical change. It means we cannot affect radioactivity by changing temperature or pressure. Radioactivity is a spontaneous process of nuclear disintegration. Lead is heaviest stable atom. In fact all radioactive elements are finally converted into lead. In beta^(-) decay |
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Answer» mass number remains UNCHANGED and ATOMIC number increases by 1. |
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| 15. |
In a common but dangerous prank, a chair is pulled away as a person is moving downward to sit on it, causing the victim to land hard on the floor. Suppose the victim falls by 0.50 m, the mass that moves downward is 75 kg, and the collision on the floor lasts 0.088 s. What are the magnitudes of the (a) impulse and (b) average force acting on the victim from the floor during the collision? |
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Answer» |
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| 16. |
The K.E. per unit mass of hydrogen at N.T.P. is |
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Answer» `1.69xx10^6` J/kg |
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| 17. |
In a ceiling fan, each blade rotates in a circle of radius of 0.5 m, If the fan makes 20 revolution per second and if the vertical component of earth's field is 8xx10^(-5) Wbm^(-2), calculate the p.d. developed between the ends of each blade. |
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Answer» |
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| 18. |
Two atmospheric sound sources A and B emit isotropically at constant power. The sound levels betaof their emissions are plotted in Fig. versus the radial distance r from the sources. The vertical axis scale is set by beta_1 = 85.0 dB and beta_2 = 65.0 dB . What are (a) the ratio of the larger power to the smaller power and (b) the sound level difference at r = 23 m? |
| Answer» SOLUTION :`~~ 1.35 XX 10^4 m` | |
| 19. |
Calculate the amount ofwork done to dissociate a system of three charge 1muC,1muCand-4muC placed on the vertices of an equilateral triangle of side 10 cm. |
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Answer» SOLUTION :`q_(A)=1xx10^(-6)C=q_(B)` `q_(C)=-4XX10^(-6)C` `r=10cm=0.1m`  Work done `=W_(AB)+W_(BC)+W_(AC)` `=(1)/(4piepsilon_(0)r)[q_(A)q_(B)+q_(B)q_(C)+q_(C)q_(A)]` `=9xx10^(9)xx(1)/(0.1)[1xx1-4xx1-4xx1]xx10^(-12)` `=(-9xx10^(9)xx7xx10^(-12))/(0.1)` `=-.63J` |
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| 20. |
Which of the following is used for line-of -sight (LOS) communication? |
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Answer» sky WAVES |
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| 21. |
A particle undergoes damped harmonic motion. The spring constant is 100N/m, the damping constant is 8.0 xx 10^(-3)kg m//s, and the mass is 0.50kg. If the particle starts at its maximum displacement, x= 1.5m at time t=0, what is the particle's position at t= 5.0s? |
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Answer» `-1.5m` |
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| 22. |
Whichof the following materials hasgot the maximum retentvity ? |
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Answer» Copper |
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| 23. |
A spring of spring constant 2N//m elongates by 4 cm. Its potential energy is approximately equal to |
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Answer» `1 xx 10^4 CAL` |
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| 24. |
The pair of particles which have same acceleration in a uniform electric field is |
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Answer» PROTON and Deuteron |
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| 25. |
A sphere of mass 50gm is suspended by a string in an electric field of intensity 5NC^(-1) acting vertically upward. If the tension in the string is 520 milli newton, the charge on the sphere is (g = 10 ms^(-2)) |
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Answer» `4 XX 10^(-3)C` |
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| 26. |
A disc of radiusis rotatating with angular frequency 10 rad/sec. A block of mass 2 kg is to be put on the disc frication coefficient between disc and block ismu_(K)= 0.4, then find the maximum distance from axis where the block can be placed without slidding: |
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Answer» Solution :`mu_(K)g = omega^(2)g` `0.4 xx 10 =(10)^(2) x` `x = 4/100 m = 4 cm` |
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| 27. |
No .of photon emitted eery second from 60 W bulb will be ……… |
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Answer» <P>`3XX10^(20)` `therefore n(plambdat)/(hc)=(60xx60xx10^(-8)xx1)/(6.6xx10^(-34)xx3xx10^(8))=2xx10^(20)` |
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| 28. |
Unpolarized light is incident on a plane sheet of water surface. The angle of incidence for which the reflected and refracted rays are perpendicular to each other is (mu of water =4/3 ) |
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Answer» a. `sin^(-1)(4/3)` |
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| 29. |
The Grandmother is portrayed as ? |
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Answer» SLIGHTLY bent |
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| 30. |
The photoelectric threshold wavelength for a certain metal is 4000A^(@). The maximum energy of the ejected photoelectrons by a radiation of 2000A^(@) is |
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Answer» 2.13 eV |
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| 31. |
A nuclear fission reactor, designed to produce electric power at a uniform rate, makes use of the phenomenon of ................ . |
| Answer» SOLUTION :CONTROLLED NUCLEAR CHAIN REACTION | |
| 32. |
What speed should a galaxy move with respect to us so that the sodium line at 589.0 nm is observed at 589.6 nm ? |
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Answer» Solution :Here `Deltalamda=lamda.-lamda=589.-589=0.66nm` `impliesDeltalamdagt0` `implies` Wavelength increases (or frequency decreases) `implies` Corresponding spectral line will be obtained towards red end of spectrum. Such phenomenon is called "Red SHIFT", which shows that galaxy is moving away from us. For red shift, RADIAL outward velocity of galaxy (or velocity of galaxy away from us) is given by formula, `v=c((Deltalamda)/(lamda))` `=3xx10^(8)((0.6xx10^(-9))/(589xx10^(-9)))` `=0.003056xx10^(8)` `:.v=3.056xx10^(5)m//s` Note: When source of light MOVES towards us, we obtain "Blue Shift", DUE to decrease in wavelength (or increase in frequency). At this time, velocity of source of light towards us is given by formula, `v=-c((Deltalamda)/(lamda))` (Where `Deltalamda=lamda.-lamdalt0` because `lamda.ltlamda`) What speed should a galaxy move with respect to us so that the SODIUM line at 600 nm is observed at 605.0 nm? |
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| 33. |
A body ascends a slope with a speed of 10 m/s . If 10% of energy of the body is lost due to friction, the height to which the body will rise (g=10m//s^2) |
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Answer» A. 0.5 m |
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| 34. |
Two radio stations broadcast their programmes at the same amplitude A, and at slightly different frequencies (Oj and co2 respectively, where omega_(2) - omega_(1) = 10^(3) Hz . A detector receives the signals from the two stations simultaneously. It can only detect signals of intensity ge 2A^(2).The time interval between successive maxima of the intensity of the signal received by the detector is 10^(-n) sec. Find n |
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Answer» |
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| 35. |
Light is incident normally on a diffracting grating through which the first diffraction is seen at 32^(@). In this case the second ordei diffraction will be ...... |
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Answer» `80^(@)` `d sin theta_(n)=n lambda` for first order minimum `:.d sin 32^(@)=1 xx lambda rArr lambda= d sin 32^(@)` Now, for second order minimum `d sin theta_(2)= 2xx lambda` `:. D sin theta_(2)=2xx d sin 32^(@)` `:. sin theta_(2)=2xx sin 32^(@)` `=2xx0.529` `sin theta_(2)=1.06` but the value of sin NEVER be GREATER than 1 so second order minimum cannot OCCUR. |
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| 36. |
Water from a hosepipe of radius 5 cm strikes a wall at a speed of 5ms^(-1) normally and stops. The force exerted on the wall in newton is |
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Answer» `13.5pi` |
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| 37. |
Due to fall in main voltage, the temperature of filament of a bulb falls from 3000 K to 2000 K. What is the percentage fall in power consumption ? |
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Answer» `75.25` `:.(P_(1))/(P_(2))=((T_(1))/(T_(2)))^(4)=((3000)/(2000))^(4)=(81)/(16)` `(P_(2))/(P_(1))=(16)/(81)""rArr""1-(P_(2))/(P_(1))=1-(16)/(81)%` FALL in power `(P_(1)-P_(2))/(P_(1))xx100=(81-16)/(81)xx100` `=80*25%` Hence the CORRECT choice is (b). |
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| 38. |
A block of mass m is connected to another block of mass M by a spring (massless) of spring constant k. The blocks are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is unstretched. Then a constant force F starts acting on the block of mass M to pull it. Find the force on the block of mass m. |
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Answer» `(MF)/(M)` |
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| 39. |
A radioactive sample has N_(0) active atoms at t=0. If the rate of disintegration at any time R and the number of atoms is N, then the ratio R/N varies with time as |
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Answer»
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| 40. |
Consider the following statements A) If time constant is small the condenser discharges slowly. B) For small values of inductance the rate of decay of current will be large |
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Answer» Both are correct |
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| 41. |
In a prism which of the following phenomena may take place __________ . |
| Answer» Answer :D | |
| 42. |
An organ pipeP_1 , closed at one end and containing a gass of densityP_1 is vibrating in the harmonic. Another organ pipe P_2 is vibrating in its third harmonic. Both the pipes are in resonance with a giventuning fork. If the compressbility of gases is equal in both pipes, the ratio of the lenghth ofP_1 and P_2 (assume the given gases to be monoatonic). |
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Answer» `1/3` `n_1=(3V_2)/(2l_2)` At RESONANCE ,`n_1=n_3` `implies V_1/(4l_1)=(3V_2)/2L_2` `implies l_2/l_1=6xxsqrt(B/P_2)SQRT(P_1)/B` `implies l_1/l_2=1/6sqrt(P_2)/P_1` |
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| 43. |
A bar magnet had a dipole moment of 5 Am^2 . The magnetic induction produced by it at apoint at distance of 50 cm from either pole : |
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Answer» ` 2 xx 10^(-6) Wb/m^2` |
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| 45. |
In a region of space, there is a possiblity of electric or magnetic field. We have to distinguish whether it is electric or magnetic field, using charged particles of same polarity, which can be fired in the field. This can be done by firing charges |
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Answer» perpendicular to the field |
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| 46. |
In accordance with Bohr's model, find the quantum number that characterises Earth's revolution around the sun in an orbit of radius 1.5 xx10^(11)mWith orbital speed 3xx10^(4)ms^(-1) (mass of the earth =6.0xx10^(24)kg) |
| Answer» SOLUTION :`2.6 XX 10^(74)` | |
| 47. |
White light is incident normally on a glass slab inside the glass slab, |
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Answer» all COLOURS travel with the same speed |
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| 48. |
Path difference and phase difference are related by the formula____. |
| Answer» SOLUTION :`DELTAPHI = (2PI)/LAMBDA DELTAX` | |
| 49. |
The electric potential as a function of distance 'x' is shown in the figure . Draw a graph of the electric field E as a function of x. |
| Answer» Solution :We know that ELECTRIC field `E = - (dV)/(DX)` . Hence the graph of the electric field E as a FUNCTION ofx will be as SHOWN here . | |
