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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. |
Draw resistivity rarr temperature (rho rarr T) graph for metals , alloys and semiconductor. |
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Answer» Solution :`rArr` (a) For METALS relation between RESISTIVITY and temperature is given by,`rho_(T) = rho_(0)[1 + alpha (T- T_(0))]` hence, relation between `rho_(T)` and T will be straight line. `rArr` At temperature much lower than `0^(@)` C the graph will be different than straight line and will be as shown in figure below  `rArr` At room temperature graph is a straight line. (b) Nichrome (alloy of nickel, iron, chromium) bas large resistivity and has weak dependence of resistivity with temperature.  `rArr` Manganin and CONSTANTAN have similar properties (to resistivity less dependent on temperature) hence they are used in making standard (reference) wire bound resistors. `rArr`(c) Resistivity of semi conductor decreases with increase in temperature. For semiconductors `RHO rarr `T graph will be as shown below. 
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| 2. |
Dr. Husain became the President of India in |
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Answer» 1967 |
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| 3. |
Give the principle of cyclotron and draw the neat labelled schematic diagram of cyclotron. |
Answer» Solution :Principle: In CYCLOTRON charged particle moves in combined electric and magnetic field which are PERPENDICULAR to each other. The magnetic field makes the charged particle to MOVE along the CIRCULAR paths and the electric fields ACCELERATES the charged particle 
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| 4. |
The coordination number for a simple cubic crystal is : |
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Answer» 4 |
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| 5. |
AS 12.4 kg solid iron cylindrical wheel of radius 0.45 m is rotating about its axle in frictionless bearings with angular velocity omega=32.8 rad/s. If its temperature is now raised from 20^(@)C to 80^(@)C what is the fractional change in omega? Given that coefficient of linear exapansion of iron is 1.1xx10^(-5).^(@)C^(-1) |
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| 6. |
A potential barrier of 0.5 V exists across a p-n junction. What is the width of the depletion region if a constant electric field of magnitude 10^-5V//m exists in the depletion region ? |
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Answer» `3mum` |
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| 7. |
A wooden block is taken to the bottom of a lake of water and then released, it rise up with a |
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Answer» CONSTANT acceleration |
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| 8. |
A hollow metal sphere of radius 10 cm is charged such that the potential on its surface is 80 V. the potential at the centre of the sphere is |
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| 9. |
Calculate the activity of 1 mg of a radioactive sample whose mass no. is 90 and half life is 28 years. |
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| 10. |
A spaceship, moving away from Earth at a speed of 0.850c, reports back by transmitting at a frequency (measured in the spaceship frame) of 100 MHz. To what frequency must Earth receivers be tuned to receive the report? |
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| 11. |
In the circuit given , the current through the zener diode is |
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Answer» a) 10 m A |
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| 12. |
Which is in thedecreasing order of boiling pointsof V group hydrides ? |
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Answer» `NH_(3)gt PH_(3) gtAsH_(3) gt SbH_(3)` `SbH_(3) gt NH_(3) gt AsH_(3) gt PH_(3)` |
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| 13. |
A Zenerdiode is fabricatedbyheavily dopingboth p- andn-sidesof the junctions. Explain,why ? Brieflyexplainthe use of zenerdiodeas a do voltageregularor with the help of a circuitdiagram. |
Answer» Solution :Zener DIODE is fabricated by heavily doping of `p-n` side ofjunction so asto operatescontinuously withoutgetting damagedin the regionof reversebreakdown voltage.  Zener Diode as Voltage Regulator: Zenerdiode is used in regulatingfluctuating voltageas shown. It is connectedcircuit through RESISTANCER depending on volatage or power rating R, is connected in parallel and output is received . Om an ABRUPT increaseof voltage across diodebecomesconstant, EQUAL to breakdownvoltage but currentrisessharply. Hence,there is an increasein VOLTAGEDROP R. As `R_(L)`is in parallelso voltageacross `R_(L)`is same. |
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| 14. |
A certain material has refractive indices 1.56, 1.60 and 1.68 for red, yellow and violet light respectively. (a) Calculate the dispersive power. (b) Find the angular dispersion produced by a thin prism of angle 6° made of this material. |
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Answer» `mu_y=1.60, and mu_c=1.68` a. Dispersive power `=omega` `=(mu_v-mu_r)/(mu_y-1)=(1.68-1.56)/(1.60-1)` `=0.12/0.60=0.2` B. ANGULAR dispersion `=(mu_r-mu_r)a` `=(0.12)xx6^@=0.72^@` |
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| 15. |
A ray of mono- chromatic light is incident at the angle theta_(i) on refracting face of a prism of apex angle 75^(@). After refraction though prism it is incident on 2nd refracing surface, such that it grazes the surface. Refractive index of material of prism is sqrt(2). If critical angle of material of prism is theta_(c). Then find the ratio (theta_(i))/(theta_(c)) |
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Answer» |
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| 16. |
A solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid the current will |
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Answer» INCREASE |
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| 17. |
Besides its use in strong charge ,a capacity is a key element of most ac circuits.What are the factors on which capacitance of a parallel plate air capacitor depends |
| Answer» SOLUTION :`C=(epsilon_0A)/d` | |
| 18. |
(i) Obtain the expressionfor the cyclotron frequency. (ii) A deutron and a proton are acceleratedby the cyclotron. Can both the accelerated with the same oscillatorfrequency ? Give greason to justify your answer. |
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Answer» SOLUTION :Derivation of the expression for cyclotron frequency. `(MV^(2))/r=qvB` `r=(mv)/(qB)` FREQUENCEY of revolution `(v)=1/("Time period")=v/(2pir)` `v=(qB)/(2pim)` |
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| 19. |
Draw a diagram of permitted transitions between the terms .^(2)P_(3//2) and .^(2)S_(1//2) in a weak magnetic field. Find the displacements (in rad//units) of Zeeman components of that line in a magnetic field B= 4.5kG. |
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Answer» Solution :For the `.^(2)P_(3//2)` LEVEL `g=4//3` (SEE above) and the energies of sublevels are `E'=E'_(0)-(4)/(3)mu_(B)M'Ƶ` where `M'Ƶ= +-(1)/(2)` for the four sublevels For the `.^(2)S_(1/2)`level, `g=2` (since `L=0`) and `E=E_(0)-2mu_(B)BM_(Ƶ)` where `M_(Ƶ) = +-(1)/(2)` PERMITTED transitions must have `DeltaM_(Ƶ)=0, +-1` Thus only the following transitions occur `{:((3)/(2),rarr,(1)/(2),,),(-3//2,,rarr,,-1//2):}}Delta omega=+-mu_(B) B// ħ = 3.96xx10^(10)rad//s` `{:((1)/(2),rarr,(1)/(2),,),(-(1)/(2),,rarr,,-(1)/(2)):}} Delta omega= +-(1)/(3)mu_(B) B// ħ= 1.32xx10^(10) rad//s` `{:((1)/(2),rarr,-(1)/(2),,),(-(1)/(2),,rarr,,(1)/(2)):}} Delta omega= +-(5)/(3) (mu_(B)B)/( ħ)= 6.6xx10^(10) rad//s` These six lines are shown below 
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| 20. |
A carbon resistor of(47 pm 4.7) k Omega is to be marked with rings of different colours for its marked with rings of different colours for its identification. The colour code sequence will be |
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Answer» GREEN - Orange - Violet - Gold R = `(47 pm 4.7) xx 10^(3) Omega` = `(47 xx 10^(3) pm 4700) Omega and (4700 xx 100)/(47000)= 10%` `= (47 xx 10^(3) pm 10% ) Omega` From colour code, `4 RARR` yellow, 7 `rarr` violet , 3 `rarr` orange, 10 % for gold. |
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| 21. |
A charge Q is placed at a distance of 4R above the centre of a disc of radius R. The magnitude of flux through the disc is phi. Now a henispherical shell of radius R is placed over the disc such that it forms a closed surface. The flux through the curved taking direction of area vector along outward normal as positive , is |
| Answer» ANSWER :C | |
| 22. |
The ratio of the speed of sound in nitrogen gas to that in helium gas, at 300 K is |
| Answer» Answer :C | |
| 23. |
What is the distance of closest approach of an alpha particle to a silver nucleus is the kinetic energy of the alpha particle is 0.40 MeV. |
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Answer» |
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| 24. |
A 8 mu F capacitor is charged by a 400 V supply through 0.1 M Omega resistance. The time taken by the capacitor to develop a potential difference of 300V is : (Given log_(10)4 = 0.602) |
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Answer» 2.2 sec |
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| 25. |
How can you lower a 100 kg body from the roof of a house using a cord with a breaking strenght of 80 kg weight without breaking the rope? (1 kg weight = g N) |
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Answer» 1.96 m/`s^2` DOWNWARDS |
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| 26. |
The centre of mass of a system of two particles of masses m_(1)andm_(2) is at a distance a_(1), from mass m_(1) and at a distance a_(2) from mass m_(2) such that : |
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Answer» `(a_(1))/(a_(2))=(m_(2))/(m_(1))` `therefore m_(1)(+a_(1))+m_(2)(-a_(2))=0`  `m_(1)a_(1)=m_(2)a_(2)IMPLIES (a_(1))/(a_(2))=(m_(2))/(m_(1))` |
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| 27. |
The magnetic induction at a point P on the axis is equal to the magnetic induction at a point on the equator of a short magnetic dipole. What is the ratio of the distances of P and Q from the centre of the dipole? |
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Answer» `2^(2//3)` It is given that `B_(P) = B_(Q)` `therefore mu_(0)/(4PI)(2M)/d_(1)^(3)=(mu_(0))/(4pi)M/d_(2)^(3)` `implies 2/d_(1)^(3)=1/d_(2)^(3) = d_(1)^(3) = 2d_(2)^(3) implies (d_(1)/d_(2))^(3)=2` `therefore` Taking the CUBE regts moth sides. we get `d_(1)/d_(2) = 2^(1//3)` |
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| 28. |
A satellite in force - free space sweeps stationary interplanetary dust at a rate (dM)/(dt)=av, Where M is the mass and v the speed of the satellite, and a is a constant. What is the deceleration the satellite experiences. |
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Answer» `-AV^(2)` |
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| 29. |
A solid conducting sphere holds more charge than a hollow sphere of the same radius when they are at same potential. |
| Answer» Solution :False - CAPACITANCE of a solid sphere is same as that of a HOLLOW sphere of same radius and has a value `C = 4 PI epsi_0r`. Hence, for a given potential charge on solid sphere is same as that on a hollow sphere. | |
| 30. |
The linear momentum of a particle as a function of time t is given by p = a+bt, where a and b are positive constants. The force acting on the particle is |
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Answer» a |
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| 31. |
Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due to |
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Answer» electrostatic FIELD lines can end on charges and conductors have free charges. Magnetostatic shielding is done by using materials of a high permeability to prevent a external magnetic field inside it. Hence, option (D) is correct. |
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| 32. |
A body of mass m_1 projected vertically upwards with an initial velocity 'u' reaches a maximum height 'h'. Another body of mass m_2 is projected along an inclined plane making an angle 30^@ with the horizontal and with speed 'u'. The maximum distance travelled along the incline is |
| Answer» ANSWER :A | |
| 33. |
In a stationary wave- |
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Answer» All PARTICLES are at REST |
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| 34. |
In a wheat stone bridge experiment to determine the unknown resistance R_(4), the values of R_(1) and R_(2) were taken to be 10 Omega and 1 Omega respectively. It was found that the galvanometer will show exact zero deflection when value of R_(3) is taken as 643 Omega lt R_(3) lt 644 Omega. Now R_(1) is changed to 100 Omega (R_(2) remains unchanged). (a) If you have been asked to obtain a balanced bridge, which values of R_(3) will you try with? (b) If balance is obtained for 6432 Omega lt R_(3) klt 6433 Omega write the measured value of unknown resistance R_(4). |
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Answer» (B) `R_(4) = 64.325 Omega` |
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| 35. |
On the axis and on the equator of an electric dipole for all points .......... . |
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Answer» (A) On both of them V`ne`0  POTENTIAL on axis (at point A) `V_(A)= (kq)/((2a+x))` and `V_(A)=- (kq)/(x)` RESULTANT potential `V=V_(A)+V_(A)=(kq)/((2a+x))-(kq)/(x) ne 0` Potential at equator (at point B) `V_(B)= (kq)/(R) ` and `V_(B)=- (kq)/(r)` wherer` =SQRT(a^(2)+y)` `:.` Resultant electric potential `V= V_(B) +V_(B)` `(kq)/(r)-(kq)/(r) =0` |
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| 36. |
A river is flowing from west to east at a speed of 5 metres per minute. A man on the south block of the river capable of swimming at 10 metres per minute in still water, wants to swim across the river in shortest time, he should swim in the direction. |
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Answer» DUE NORTH |
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| 37. |
A block A slides over another block B which is placed over a smooth inclined plane. The coefficient of friction between the two blocks. A and B is mu. Mass of block B is two times the mass of block A. The acceleration of the centre of mass of two blocks is |
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Answer» `g sin theta` |
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| 39. |
The electric potential of earth is taken to be zero because earth is a good |
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Answer» insulator. |
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| 40. |
The capacity of an isolated conducting sphere of radius 'R' is proportional to |
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Answer» `R^2` |
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| 41. |
The magnetic potential at a point on the axial line of a bar magnet dipole moment M is V. What is the magnetic potential due to a bar magnet of dipole moment M/4 at the same point ? |
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Answer» 4 V |
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| 42. |
Ray of light moving in water incidents on glass plate. Reflected light becomes completely plane polarised when incident at 51^(@), so refractive index of glass will be ...... [Refractive index of water 1.3 and tan 51^(@)=1.235] |
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Answer» <P>`1.33` `:.n_(g)=n_(w)tan51^(@)` `=1.3xx1.235` `1.6055=1.605` |
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| 43. |
What do you mean by crooks? |
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Answer» a helpful person |
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| 44. |
How can a given light be unpolarized, plane polarised and partially plane polarised can be determined ? |
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Answer» Solution :Incident the given light perpendicularly to ONE side of polaroid. Taking a incident ray as axis of polaroid rotate the polaroid and check the intensity of light emergent from it. If a full rotation given to the polaroid and the intensity of emerging light does not change then the light is unpolarised. If a full rotation given to the polaroid and the intensity of emerging light becomes TWO times zero and two times MAXIMUM then the given light is plane polarised light. If a full rotation given to the polaroid and the intensity of emerging light becomes two time maximum and two times minimum (not zero then the given light is PARTIALLY plane polariser light. |
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| 45. |
A currentof 10 Ais maintained in a conductorof cross-section1 cm^(2). If thenumberof densityof freeelectrons be 9 xx 10^(28)m^(-3),the dirftvelocityoffree electrons is . |
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Answer» `6.94xx 10^(-6) m//s` |
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| 46. |
A wire having mass m and length 1 can freely slide on a pair or parallel smooth horizontal rails placed in vertical magnetic field B. The rails are connected by a capacitor of capacitance C . The electric resistance of the rails and the wire is zero .If a constant force F acts on the Wire as shown in the figure . Then ,the acceleration of the wire can be given as |
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Answer» `a=(C^(2)B^(2)L-F)/(m)` |
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| 47. |
वे सभी प्रक्रम जो सम्मिलित रूप से अनुरक्षण का कार्य करते है, उन्हे क्या कहते है ? |
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Answer» जैव प्रक्रम |
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| 48. |
A parallel plate capacitor has its two plates connected to an ideal spring of force constant K. Relaxed length of spring is L and it is made of non conducting material. The area of each plate is A. The capacitor has a charge q_(0) on it. To discharge the capacitor through the resistance R, switch S is closed. If the time constant of the circuit is very large and discharge process is very slow, how much heat will be dissipated in the resistance? Assume that there is no friction and the plates always remains parallel to each other. |
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Answer» |
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| 49. |
Welders wear special goggles or face masks with glass windows to potect their eyes from electromagnetec radiations. Name the radiations and write the range of their frequency. |
| Answer» SOLUTION :Welders wear special goggles with glass WINDOWS to protect the eyes from ULTRA violet rays (UV rays). The range of UV rays is `4 xx 10^(-7)` m (400 nm) to `6 xx 10^(-10)` m (0.6 nm). | |
