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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. |
Determine the equivalent resistance of networks shown in Fig.(i) and (ii). |
Answer» Solution : (i) The circuit contains four identical elements joined inseries. One such element is shown in Fig.and hastwo branches, having resistance of 2 `Omega (i.e., 1 Omega +2 Omega)`and 4 12 (i.e., 212 +212) respectively, joined in PARALLEL.` therefore ` Resistance of the element`R = (2 xx 4)/(2 + 4) = 8/6= 4/3 Omega` For whole series net equivalent resistance = `4R = 4 xx4/3 =16/3Omega` (ii) The combination shown has five RESISTANCES all joined in series. The total resistance is,thus, 5R. |
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| 2. |
Polarising angle for water is 53^@4' . If light is incident at this angle on the surface of water and reflected , the angle of refraction is : |
| Answer» Answer :C | |
| 3. |
Vector form of a law can be written as vec J=σvecE. The above equation is an equivalent form of a famous law. Name the law. |
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Answer» Biot-Savart.s law |
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| 4. |
A concave mirror is placed on a horizontal table, withits axis directed vertically upward. Let O be the pole of the mirror and C its center of curvature. A point object is placed at C. It has a real image, also located at C. If the mirror is now filled with water, the image will be |
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Answer» real, and will REMAIN at C 
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| 5. |
An electro magnetic wave in vacuum has the electric and magnetic fields vecE and vecB which are always perpendicular to each other. The direction of polarisation is given by vecX and that of wave propagation by vecK then: |
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Answer» `vecX|\|vecB` and `vecK|\|vecBxxvecE` |
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| 6. |
If 'P' is the middle point on the axis of a solenoid then derive the expression for magnetic field at that point. |
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Answer» <P> Solution :`""costheta=(L/2)/sqrt(r^(2)+l^(2)/4)""(##SPH_ABT_PHY_QB_XII_C04_E03_001_S01.png" width="80%">i.e., `""costheta=l/2 times 2/sqrt(4r^(2)+l^(2))=l/sqrt(4r^(2)+l^(2))` here `""B_(p)=(mu_(0)/(4PI))((2pini)/l)(2costheta)` i.e., `""B_(p)=mu_(0)Ni(l/sqrt(4r^(2)+l^(2)))=(mu_(0)NIL)/sqrt(4r^(2)+l^(2)) " where " N=n/l` `therefore ""B_(p)=(mu_(0)ni)/sqrt(4r^(2)+l^(2))` |
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| 7. |
Find the thickness of the wire The main scale division is of 1mm In a complete rotation the screw advances by 1mm and the circular scale has 100 devisions |
| Answer» Solution :EXCESS reading (ZERO error) = 0.03mm It is giving 7.67 MM in which there is 0.03mm excess reading which has to be removed (SUBTRACTED) so actula reading `=7.67 - 0.03 = 7.64 mm` . | |
| 8. |
A graph between the square of the velocity of a particle and the distance(s) moved is shown in figure. The constant acceleration of the particle in kilometer per hour square is: |
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Answer» `2250` |
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| 9. |
Find the torque on M_(1) due to M_(2) |
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Answer» Solution :DUE to `M_(2)`, magnetic fields at `S` and `N` of `M_(1)` are `B_(1)` and `B_(2)` RESPECTIVELY. The forces on `-m` and `+m` are `F_(1)` and `F_(2)` as shown in the figure.The torque (about the centre of the dipole `m_(1)`) will be `F_(1)a+F_(2)a=(F_(1)+F_(2))a` `[(mu_(0)/(4pi))M_(2)/((R-a))m+(mu_(0)/(4pi))M_(2)/((r+a))m]a` `(mu_(0)/(4pi))M_(2)m(1/r^(3)+1/r^(3))a :' alt LT r` `(mu_(0)M_(2)m)/(4pi)2/r^(3)a=(mu_(0)M_(1)M_(2))/(4pi^(3))` 
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| 10. |
If the resultant of vecA and vecB makes angle alpha with vecA and beta with vecB, then |
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Answer» `alpha lt BETA` ALWAYS 
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| 11. |
Focal length of the objective of a terrestejal telescope is 80 cm and it is adjusted for parallel rays, then its magnifying power is 20. If the focal length of erecting lens is 20 cm, then full length of telescope will be (in cm) |
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Answer» 84 |
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| 12. |
When unpolarized light incidents on polarizer 3.14 rad/s angular speed and area 3 xx 10^(-4) m^(2) with energy 3 * 10^(-3) J, then find energy of polarized light in each rotation |
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Answer» `47.1xx10^(-4)J` `:.(2pi)/(T)=3.14` `:.T=(2xx3.14)/(3.14)` `:. T=2s` Average intensity `lt I gt =(I_(0)+0)/(2)=(I_(0))/(2)` `=(3xx10^(-3))/(3xx10^(-4)xx1xx2)` `lt I gt -(10)/(2)J` Energy polarized in each rotation `E= lt I gt xx "AREA" xx` Angular SPEED `=(10)/(2)xx3xx10^(-4)xx3.14=47.1xx10^(-4)J` |
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| 13. |
Chaitanya pedals a stationary bicycle at one revolution per second. The pedals are attached to 100 turns coil of area 0.1m^(2) and placed in a uniform magnetic field of 0.1T. What is the maximum voltage generated in the coil? |
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Answer» Solution :`E_(0)= NB A OMEGA = NBA (2PI v)` `E_(0)= 100 XX 0.1 xx 0.1 (2 xx 3.14 xx 1) V= 6.28V` |
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| 14. |
Where on the surface of Earth is the vertical component of earth's magnetic field zero ? |
| Answer» SOLUTION :On the EQUATOR S, the vertical COMPONENT of earth.s MAGNETIC FIELD is zero. | |
| 15. |
(A): The electric field induced due to changing magnetic field is non-conservative. (R): The line integral of the electric field along a closed loop is always zero. |
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Answer» Both A and R are TRUE and R is the correct explanation |
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| 16. |
O is a point object kept on the principal axis of a concave mirror M of radius of curvature 20cm. P is a prism of angle 1.8^@ . Light falling on the prism (at small angle of incidence) gets refracted through the prism and then falls on the mirror. Refractive index of the prism is 3//2 . Find the distance between theimages formed by the concave mirror due to this light. |
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Answer» `=(1.5-1)1.8^(@)` `=(0.5)1.8xx(pi)/(180)rad=(pi)/(200)rad` `:.` Distance `OO_(1)=10xx(pi)/(200)=(pi)/(20)cm` Similarly, distance `OO_(2)=(pi)/(20)cm` `:. O_(1)O_(2)=(pi)/(10)cm` For the mirror, `O_(1)` and `O_(2)` are two point OBJECTS, at a distance of30cm. Now, applying mirror FORMULA `(1)/(v)+(1)/(-30)=(1)/(-10)rArrv=-15cm` Latent magnificationis `-(v)/(u)=((-15))/(-30)=-(1)/(2)` `(-ve` sign indicates INVERTED image `)` Therefore, if `O_(1)^(')` and`O_(2)^(')` are the images formed, then distance between them, `O_(1)^(')O_(2)^(')=(1)/(2)O_(1)O_(2)=(1)/(2).(pi)/(10)=(pi)/(20)cm` 
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| 18. |
A T.V transmission tower at a particular station has height 160 m, earth's radius is 6400 km. What is population covered if population density is 1200 // km^(2) |
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Answer» 50 lac `= PI d^(2) xx rho=(22)/(7) xx (45.25)^(2) xx 1200=77.24 ` lac. |
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| 19. |
Look at the graphs (a) to (d) carefully and indicate which of these possibly represents one dimensional motion of a particle ? |
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Answer»
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| 20. |
Obtain the formula of intensity if the phase difference at a point from two sources is phi. |
Answer» Solution : Suppose point G as shown in figure and let the path difference between TWO displacement be `phi` at that point. If the displacement produced by `S_(1)` at G is `y_(1)=acosomegat` then the displacement produced by `S_(2)` at G would be `y_(2)=ACOS(omegat+phi)`. The resultant displacement according to SUPERPOSITION principle `y=y_(1)+y_(2)=acosomegat+acos(omegat+phi)` `=a[cosomegat+cos(omegat+phi)]` `=2acos""(phi)/(2).cos(omegat+(phi)/(2))` `[:.cosA+cosB=2cos((A+B)/(2))cos((A-B)/(2))]` AMPLITUDE of resultant displacements `=2acos((phi)/(2))` and and intensity of point G, `Iprop4a^(2)cos^(2)""(phi)/(2)` `I=4I_(0)cos^(2)((phi)/(2))""[:."t=where "I_(0)propa^(2)]` If this equation is obeyed, then the CONSTRUCTIVE interference will formed at point G and interference leading to maximum intensity. For maximum intensity from this equation, `phi=0,pm2pi,pm4pi`...... for the value `phi`, then constructive interference will formed and interference leading to maximum intensity. Reverse from this equation, if at point G `phi=pmpi,pm3pi,pm5pi.....,` for the value of o, then destructive interference will formed and leading to zero intensity. |
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| 21. |
The phase and orientation of the magnetic vector associated with electromagnetic oscillations differ respectively from those of the corresponding electric vector by : |
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Answer» ZERO and zero |
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| 22. |
Read the following statements and find out the incorrect statement(s). a. Human are sexually reproducing and viviparous.b. Transfer of sperm in female genital tract (vagina ) is called ejaculation.c. There are remarkable differences between the reproductive events in the male and in the female.d. Sperm formation continues even in old men, but formation of ovum ceases women around the age of fifteen years. e. The male and female reproductive systems are located in the pelvic region. |
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Answer» a, C and d |
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| 23. |
Root cell of wheat has 42 chromosomes. What would be the number of chromosomes in the synergid cell ? |
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Answer» 7 |
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| 24. |
The fringes in the interference pattern become narrower if the entire double-slit experimental set up is immersed in water. |
| Answer» SOLUTION :True-In WATER `beta_(water)=(beta_(AIR))/(n_(water))`. | |
| 25. |
Magnetic flux linked with a circuit of resistance 100 12 increases from 10 Wb to 60 Wb in 0.1 s. The total amount of induced charge is _____. |
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Answer» |
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| 26. |
When had Mini shifted to the new place? |
| Answer» Answer :A | |
| 27. |
At t = 0, time in L-C oscillator circuit ……. |
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Answer» CHANGE in Q is MAXIMUM |
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| 28. |
A 12 pF capacitor is connected to a 50 V battery. How much electrostatic energy is stored in the capacitor ? |
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Answer» Solution :Here C = 12 PF `= 12 XX 10^(-12)F and V = 50 V` `:.` Energy stored `u = 1/2 CV^2 = 1/2 xx 12 xx 10^(-12) xx(50)^2 = 1.5 xx 10^(-8)J.` |
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| 29. |
Formation of covalent bonds in compounds exhibits …….nature. |
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Answer» wave Moving ELECTRON in ATOM act as wave means electron have wave forms. |
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| 30. |
A point charge .q. is placed at the centre of an uncharged conuducting shell of inner radius R and outer radius 2R. If the point charge is removed from the centre of the shell, to infinity (without any electric contact with the shell). Work done by electric force is |
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Answer» `(Q^(2))/(16piin_(0)R)` |
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| 31. |
The half-life of ""^(215)Atis 100mus . Find the time taken for the radioactivity of a sample of ""^(215)At to decay to 1/(16)thof its initial value: |
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Answer» `400mus` |
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| 32. |
Paragraph : A spaceship traveling east flies directly over the head of an inertial observer who is at rest on the Earth's surface. The speed of the spaceship can be found from this relationship: sqrt(1-v^(2)//c^(2))=1//2. An apple falls from a tree and takes 4 s to reach the ground as reported by the Earth-bound observer. According to the navigator's instruments, how long did it take the apple to fall? |
| Answer» ANSWER :C | |
| 33. |
Paragraph : A spaceship traveling east flies directly over the head of an inertial observer who is at rest on the Earth's surface. The speed of the spaceship can be found from this relationship: sqrt(1-v^(2)//c^(2))=1//2. The pilot fires an ion gun that propels ions from the space ship at 1.0xx10^(8)m//s relative to the ship. What is the speed of the ions as measured by the Earth observer? |
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Answer» `1.0xx10^(8)m//s` |
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| 34. |
(A) According to electromagnetic theory an accelerated particle continuously emits radiation ( R) : According to classical theory the proposed path of an electron in Rutherford atomic model will be parabolic |
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Answer» Both 'A' and 'R' are TRUE and 'R' is the correct EXPLANATION of 'A'. |
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| 35. |
Paragraph : A spaceship traveling east flies directly over the head of an inertial observer who is at rest on the Earth's surface. The speed of the spaceship can be found from this relationship: sqrt(1-v^(2)//c^(2))=1//2. The navigator's on-board instruments indicate that thelength of the spaceship is 20m. If the length of the ship is measured by the inertial Earth-bound observer, what value will be obtained? |
| Answer» Answer :C | |
| 36. |
A parallel beam of monochromatic light is incident normally on a plane transmision grating having 5000 lines per cm and the second order spectral ,ine is found to be diffracted through 30^(@). Calculate the wavelength of light used. |
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Answer» |
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| 37. |
Paragraph : A spaceship traveling east flies directly over the head of an inertial observer who is at rest on the Earth's surface. The speed of the spaceship can be found from this relationship: sqrt(1-v^(2)//c^(2))=1//2. The navigator of the space ship observes a neon sign on a storefront. If he measures the speed of light emitted from the sign as he approaches the sign, what value will he obtain? |
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Answer» `1.5xx10^(8)m//s` |
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| 38. |
Sharp peak point A represents |
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Answer» CHARACTERISTIC X-rays |
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| 39. |
Paragraph : A spaceship traveling east flies directly over the head of an inertial observer who is at rest on the Earth's surface. The speed of the spaceship can be found from this relationship: sqrt(1-v^(2)//c^(2))=1//2. The observer is 5 feet fall. According to the navigator of the space ship, how tall is the observer? |
| Answer» ANSWER :B | |
| 40. |
Liquid is filled in a vessel which is kept in a room with, temperature 20^(@)C. When the temperature of the liquid is 80^(@)C then it loses heat at the rate of 60 cal/second. What will be the arte of loss of heat when the temperature of the liquid is 40^(@)C ? |
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Answer» 180 cal/s Correct choice (d). |
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| 41. |
When the mass of radioactive substance is doubled, its half life |
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Answer» Is doubled |
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| 42. |
A thin straight infinitely long conducting wire having charge density lambdais enclosed by a cylinder surface of radius r and length l, its axis coinciding with the length of the wire. Find the expression for the electric flux through the surface of the cylinder. |
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Answer» Solution :As shown in a thin straight INFINITELY long conducting wire having linear charge density `lambda ` is enclosed by a cylinder SURFACE of radius r and length l with its axis COINCIDING with the length of the wire. Asper Gauss.s law TOTAL ELECTRIC flux through the entire surface of the cylinder ` phi_in =(1)/(in_0) ` (charge enclosed within the cylinder) ` = (1)/(in_0)(lambda l)=(lambda l)/(in_0) ` ` (##U_LIK_SP_PHY_XII_C01_E09_022_S01.png" width="80%"> |
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| 43. |
A sinusoidal voltage of rms value 220 V is applied to a diode and a resistor R in the circuit shown in figure so that half wave rectification occurs. If the diode is ideal, what is the rms voltage across R_1? |
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Answer» `55sqrt2` V |
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| 44. |
Two colis have a mutual inductance 0.005 H. The current changes in the first coil according to the equation where A and The maximum value of the emf induced in the second coil is |
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Answer» `2PI` `epsi= 0.005 (d)/(dt) (I_(m) sin omega t)` `epsi= 0.05I_(m) (d)/(dt) (sin omega t)` `= 0.005 I_(m) cos omega t XX omega` `= 0.005 I_(m) omega cos omega t` `= 0.005 xx 10 xx 100pi cos omega t` `epsi= 5pi cos omega t` ....(1) `epsi= epsi_(m) cos omega t` ....(2) From (1) and (2) `epsi_(m)= 5pi` |
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| 45. |
In NPN transistors, when the emitter- base junction is forward - biased , the direction of conventional current is from …………… |
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Answer» BASE to EMITTER |
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| 46. |
On placing a piece of ferromagnetic material of cross-sectional area 1cm^(2) in magnetic field of 200 oersted, flux density of 3000 Gauss is produced in it. The values of relative permeability and magnetic susceptibility of the material will respectively be - |
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Answer» 11.9 and 150 |
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| 47. |
The electric field in a region of space is given by E = 5i + 2j N/C. The electric flux due to this field through an area 2m^(2) lying in the YZ plane. In S.I. units is |
| Answer» ANSWER :A | |
| 48. |
A D.C. motor working on 200V have initial current of 5A but when it attained maximum velocity, the current obtained is 3A. What will be its Back emf ? |
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Answer» 0V Now `I=(E-EPSILON)/R rArr 3= (200-epsilon)/40` `therefore120=200-epsilon` `THEREFORE epsilon` =80 V |
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| 49. |
When two disturbances are superimposed,on what principle they combine ? |
| Answer» Solution :They combine according to the superposition principle,i.e. at any GIVEN point and INSTANT the resultant electric FIELD is VECTOR sum of individual fields. | |
| 50. |
Resistance of tungsten filament in one bulb at 20 ""^(@)C " is " 18 Omega. When this bulb is connected to 60 V source, steady current passing through it is 0.3 A. Find temperature of this filament taking alpha = 4.5 xx 10^(-3) K^(-1) . Assume that Ohm's law is obeyed. |
| Answer» SOLUTION :`THETA = 2070. 7 K` | |
