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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.
| 38051. |
Which of the following isotopes is used for treatment of cancer ? |
| Answer» Answer :B | |
| 38052. |
Assertion: Two short magents are placed ona cork which foalts on water. The magnets are placed such that the axis of one produced bisects the axis of other at right angles. Then the cork has neither translational nor rotational motion. Reason: Net force on the cork is zero. |
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Answer» If both ASSERTION and reason are true and reason correct explanation of assertion. |
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| 38053. |
A lens when placed on a plane mirror then object needle and its image coincide at 15 cm . The focal length of the lens is |
| Answer» ANSWER :a | |
| 38054. |
The voltageV and current I graph for a conductor at two different temperaturesT_(1) and T_(2) are shown in the figure. The relation between T_(1) and T_(2) is |
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Answer» `T_(1) GT T_(2)` |
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| 38055. |
What is the use of collimator? |
| Answer» Solution :The COLLIMATOR is an arrangement to PRODUCES a PARALLEL bea of LIGHT. | |
| 38056. |
A charged dust particle of radius 5 xx 10^(-7)m is located in a horizontal electric field having an intensity of 6.28 xx 10^(5)V m^(-1). The surrounding medium in air with coefficient of viscosity eta = 1.6 xx 10^(-15) Ns m^(-2) . If this particle moves with a uniform horizontal speed of 0.01 ms^(-1), the number of electrons on it will be |
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Answer» 20 |
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| 38057. |
An ideal gas consistsof molecules, each molecule being a linear chain of four atoms. If this gas is heated up to a temperature at which all degrees of freedom, including vibrational, are excited, the molar specific heat of such a gas at constant volume will be (include vibrational degrees also) |
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Answer» `(19R)/(2)` (i) three translational DEGREES of freedom, (ii) `(2xx4)=8` rotational degrees of freedom and (iii) `(2xx4)=8` VIBRATIONAL degree of freedom. (Note : Rotation axes PASS through each atom PERPENDICULAR to linear chain, and vibration can occur for each atom in a plane perpendicular to linear chain). HENCE total number of degrees of freedom = `3+8+8=19`. Hence, molar specific heat at constant volume = `19R//2`. |
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| 38058. |
A gun of mass 10000 kg fires a shot of mass 50 kg with a velocity of 250 m/s. Find recoil velocity the gun. |
| Answer» SOLUTION :MV+mv =0 or 10000v+50x250=0 or V = 10.25 m/s | |
| 38059. |
1. A coil of area 2 cm^2with turns 500 is placed in a magnetic field of 0.5 T with its plane parallel to field. The flux linked with the coil is |
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Answer» 50mwb |
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| 38060. |
Starting with a sample of pure Cu^66, 7/8 of it decays into Zn in 15 min. The corresponding half life is |
| Answer» Answer :A | |
| 38061. |
Power of a lens is -4D and for the second lens, power is +2D. The total power for the two in contact is: |
| Answer» ANSWER :C | |
| 38062. |
An energy source will supply a constant current into the load if its internal resistance is |
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Answer» Zero |
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| 38063. |
Assume that an electron is moving along an x axis and that you measure its speed to be 2.05xx10^(6)m//s, which can be known with a precision of 0.50%. What is the minimum uncertainty (as allowed by the uncertainty principle in quantum theory) with which you can simultaneously measure the position of the electron along the x - axis ? Calculations : To evaluate the uncertainty Deltap_(x) in the momentum, we must first evaluate the momentum component p_(x). Because the electron's speed v_(x) is much less than the speed of light c, we can evaluate p_(x) with the classical expression for momentum instead of using a relativistic expression. We find p_(x)=mv_(x)=(9.11xx10^(-31)kg)(2.05xx10^(6)m//s) =1.87xx10^(-24)kg.m//s. The uncertainty in the speed is given as 0.50% of the measured speed. Because p_(x) depends directly on speed, the uncertainty Deltap_(x) in the momentum must be 0.50% of the momentum : Deltap_(x)=(0.0050)p_(x) =(0.0050)(1.87xx10^(-24)kg.m//s) =9.35xx10^(-27)kg.m//s Then the uncertainty principle gives us Deltax=(h)/(Deltap_(x))=((6.63xx10^(-34)J.s)//2pi)/(9.35xx10^(-27)kg.m//s) =1.13xx10^(-18)m~~11nm, which is about 100 atomic diameters. |
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Answer» Solution :KEY IDEA The minimum uncertainty ALLOWED by quantum theory is given by Heisenberg.s uncertainty principle in Eq. 37-02. we need only consider components ALONG the x axis because we have MOTION only along that axis and what the uncertainty `Deltax` in location along, that axis. Since we want the minimum alloweduncertainty, we use the equality instead of the inequality in the x-axis part of Eq. 37-20, writting `Deltax.Deltap_(x)=H`. |
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| 38064. |
A geosynchronous satellite is |
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Answer» located at a height of 34860 km to ENSURE global coverage |
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| 38065. |
In a deflection magnetometer, the external magnet should be replaced : |
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Answer» ALWAYS in the DIRECTION RESULTANT field of EARTH |
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| 38066. |
To slide a heavy box, we generally left it a bit to place a metallic pipe below it Why ? |
| Answer» Solution :If the box is PULLED without PIPE, sliding FRICTION COMES into play while in PRESENCE of pipe, rolling friction comes into play. Since rolling friction is much less than sliding friction, it is easy to slide the box. | |
| 38067. |
The following measurement were taken for an unknown resistance X,with a P.O.Box, in Ohms |
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Answer» SOLUTION :The resistance X SATISFIES (i) 15`Omega` < X <16`Omega` (ii) 15.2 < X < 15.3`Omega` (iii) 15.24`Omega` < X <15.25`Omega` The error `~(1525-15 24)/(2)Omega=0.005Omega = 0.005 Omega` |
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| 38068. |
Below a list of four types of surfaces |
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Answer» ROUGH white |
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| 38069. |
A wooden block of mass 2m is hung with the help of a light string of length / in the vertical plane. A bullet of mass m/4 moving horizontally with velocity V_0{V_0 = sqrt(5gl)} penetrates the block and comes out with velocity v_0/2 The maximum height reached by the block is (Assume string remains vertical till bullet passes through the block) |
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Answer» `v_0^2 /(256G)` |
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| 38070. |
In Melde,s experiment,the string vibrates in 6 loops when a 30 g weight is placed inthepan of weight 10 g. To make the string to vibrates in 8 loops the10 g. mass that has to be removed form the pan is |
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Answer» ``20 g by Melde's method. The frequency of vibration of a string of length `l,` MASS per unit length m and vibrating in p loops under tension T is given by `n=p/(2l)sqrt(T/m) rArr psqrt(T) =` constant if n, `l andm ` are constant. HENCE, `T prop 1/p^(2) rArrT_(1)/T_(2) = p_(2)^(2)/p_(1)^(2)` or `((30+10))/T_(2) = (8)^(2)/(6)^(2) rArr 40/T_(2) = 64/36` `therefore T_(2)=34/64xx 40 =22.5` So, WEIGHT removed form the pan `=40 - 22.5` `=17.59` |
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| 38071. |
If the focal length of a magnifier is 5 cm, calculate (a) the power of the lens (b) the magnifying power of the lens for relaxed and strained eye. |
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Answer» SOLUTION :(a) As power of a LENS is reciprocal of focal LENGTH in m, `P=1/((5xx10^(-2)m))=1/0.05` dioptre = 20D (b) For relaxed eye, MP is minimum and will be MP = `D/f=25/5=5` While for strained eye, MP is MAXIMUM and will be MP = `1+D/f=1+5=6` |
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| 38072. |
Two prisms A and B are in contact with each other have angular dispersions of 2^(@) and 4^(@) respectively. The dispersive power of A is 0.002. If the combination produces dispersion without deviation, the dispersive power of B is |
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Answer» 0.001 |
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| 38073. |
The VC shown in the diagram has zero error in it. It is given that 9 msd= 10 vsd. (i) What is the magnitude of the zero error ? (1 msd = 1 mm) (ii) The observed reading of the length of a rod measured by this VC comes out to be 5.4 mm. If the vernier had been error free then reading of main scale would be ____ and the division of vernier scale coinciding would be ____. |
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Answer» (i) `x = – 0.5` MSD, (ii) 1, 3 |
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| 38074. |
The current from an A.C. source is given by I = 2cos(omegat + phi) then rms value of current is …… |
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Answer» Solution :Comparingequation `I=2cos(omegat+phi)` with `I=I_m cos (omegat+phi)` `I_m`=2A `THEREFORE I_(rms)=I_m/sqrt2=2/sqrt2=sqrt2A` |
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| 38075. |
Assertion : Generally heavy nuclei are unstable. Reason : It has more neutrons and protons. |
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Answer» If both assertion and REASON are true and reason is the CORRECT EXPLANATION of assertion. |
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| 38076. |
If the bar magnet in Exercise 5.13 is turned around by 180^@ , where will the new null points be located ? |
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Answer» Solution :In exercise 5.13 null points were OBTAINED along the axial line. It was possible when N-pole of magnet is oriented towards geographic south. On turning the magnet around by `180^@` , N- pole of magnet will be oriented towards geographic north and now null points will be obtained along the equatorial line of bar magnet , say at a DISTANCE `r.` , then `(mu_0)/(4pi) * (m)/(r.^3) = B_H = (nu_0)/(4pi) * (2m)/((0.14)^3) implies r.^3 = ((0.14)^3)/(2)` or `r. = (2)^(-1/3) (0.14) = 0.111 cm ` on the normal bisector. |
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| 38077. |
A 12.5eV electron beam is used to bombard gaseous hydrogen at room temperature What series of wavelengths will be emitted. |
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Answer» Solution :`E_(n)=(-13.6)/(2^(2))eV` Energy required to excite hydrogen atom from ground state to the second EXCITED state `E_("final")-E_("initial")` `=-1.51-(-13.6)=120.9eV` i.e., hydrogen atoms WOULD be excited UPTO third energy level (i.e., n = 3) second excited state, Alternatively  For Lyman `(1)/(lambda)=R[(1)/(n_(f)^(2))-(1)/(n_(i)^(2))]` or `, (1)/(lambda)=1.097xx10^(7)[(1)/(2^(2))-(1)/(3^(2))]` `rArr lamda=122nm` For Balmer `(1)/(lambda)=1.097xx10^(7)[(1)/(2^(2))-(1)/(3^(2))]` `lambda=656.3 nm` |
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| 38078. |
A straight conductor of length 32 cm carries a current of 30 A. Magnetic induction at a point in air at a perpendicular distance of 12 cm from the mid-point of the conductor is |
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Answer» 0.2 GAUSS |
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| 38079. |
An iron ring of relative permeability mu_r, has windings of insulated copper wire of n turns per unit length. When the current in the windings is I, find the expression for the magneitc field in the ring. |
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Answer» SOLUTION :If the anchor RING is an iron ring of RELATIVE permiability `mu_r`, then magentic field in iron ring will become `B = mu_0 mu_r, NI`. |
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| 38080. |
How do source and images behave as coherent sources? |
| Answer» Solution :Souce and image: In this METHOD a source and its image will act as a of COHERENT source, because the source and its image will have waves in - phase or constant phase difference. The INSTRUMENT, Fresnel.s biprism uses TWO VIRTUAL sources as two coherent source and the instrument, Lloyd.s mirror uses a source and its virtual image as two coherent source. | |
| 38081. |
In question 84, the wavelength of the wave will be : |
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Answer» 1.2 m |
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| 38082. |
The average value of rotational kinetic energy of one mole of oxygen gas at temperature T will be |
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Answer» RT |
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| 38083. |
Two capacitors with capacitances C_(1) and C_(2) are connected in parallel. Find the resultant capacitance. |
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Answer» SOLUTION :When the capacitors are connected in PARALLEL (Fig. 24.9), all their interconnected plates have the same potential, therefore `q_(1)=C_(1)( varphi_(1)-varphi_(2)) and q_(2)=C_(2)(varphi_(1)-varphi_(2))`, where `q_(1) and q_(2)` are thecharges of the RESPECTIVE capacitors. The charge of the system is `q=q_(1)+q_(2)=(C_(1)+C_(2)) (varphi_(1)-varphi_(2))`. On the other h and `q=C(varphi_(1)-varphi_(2))`, where C is the equivalent capacitance. Hence the formula sought. 
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| 38084. |
A body is projected with a velocity u at an angle of 60^@ to the horizontal. The time interval after which it will be moving in a direction of 30^@ to the horizontal is |
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Answer» `U//(sqrt(3)G)` |
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| 38085. |
What is rectification? With relevant circuit diagram and waveforms explain the working of P-N junction diode as a full-Wave rectifier. |
| Answer» SOLUTION :The process of CONVERTING alternating CURRENT/ VOLTAGE into direct current/ voltage. | |
| 38086. |
The radioactive isotopes 'D' decays according to the sequence. D overset(beta^-)toD_1oversetalphatoD_2 If the mass number and the atomic number of D_2 are 176 and 71 respectively. What is the atomic number of D ? |
| Answer» SOLUTION :ATOMIC number=72 | |
| 38087. |
Two particles of the same mass m are suspended through strings of equal length l in such a manner that points of suspension are distance d apart. Both particles carry charges of same magnitude but of opposite polarity. Calculate the magnitude of charge if strings make an angle theta with the vertical. |
| Answer» Solution :`((4piepsilon_0 MG (d-2l SIN theta)^2 sin theta)/(COS theta ))` | |
| 38088. |
The radioactive isotopes 'D' decays according to the sequence. D overset(beta^-)toD_1oversetalphatoD_2 If the mass number and the atomic number of D_2 are 176 and 71 respectively. What is the mass number of D ? |
| Answer» SOLUTION :MASS number=180 | |
| 38089. |
Number of integral values of 'a' for which (a-5)x^2 - 2ax + (a-4)=0 , has exactly one root in(0, 2), is |
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Answer» 18 ROOTS lies in the INTERVAL (0,2) f(2)=4a -20-4a+a-4=(a-24) f(0).f(2) lt 0 (a-4)(a-24) lt 0 a `in`(4,24 ) For a=4 `-x^2-8x=0` `x(x+8)=0 rArr r=0,-8` So a=4 is not possible For a=24 `19x^2 -48x +20=0` `19x^2 -38x -10x +20=0` (x-2)(19x-10)=0 `x=2,10/19` So , a =24 is possible so, a `in` (4,24) |
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| 38090. |
If a ray of light is incident on a plane mirror at an angle of 30^@, then deviation produced by a plane mirror is ....... |
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Answer» `30^@` angle of incident = angle of reflection incident  From the geometry of figure, angle of deviation `=180^@-i-r=180^@-30^@-30^@=120^@` |
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| 38091. |
When a bar magnet is divided into two pieces, |
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Answer» both the PIECES lose MAGNETISM. |
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| 38092. |
Biot-Savart law can be expressed alternatively as |
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Answer» COULOMB's LAW |
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| 38093. |
The combination of gates shown below yields : |
| Answer» Solution :It is an OR Gate. | |
| 38094. |
The astronomical microscope consists of objective and eyepiece. The focal length of the objective is |
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Answer» EQUAL to that of the eyepiece |
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| 38095. |
Which of the following is best conductor of heat ? |
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Answer» Water Hence correct CHOICE is (d). |
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| 38096. |
An AM wave is represented by C_m (t)=6(1+0.5sin12560t)xxsin22xx10^5t. calculateamplitude of carrier wave. |
| Answer» SOLUTION :`omega_c=22xx10^5Hz` | |
| 38097. |
Pick the odd one out. |
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Answer» INTERFERENCE |
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| 38098. |
In a potentiometer experiment why is it necessary ot used a long wire? Length and resistance of a potentiometer wire are 4 m and 10Omega respectively. It is connected to a cell of emf 2 volt. Another cell when joined to this potentiometer and null point is measured at 250 cm. Find out the emf of the second cell. |
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Answer» Solution :In different measurements using a potentiometer, the ratio `(L)/(L)` often comes in the WORKING formula. Here, L = length of the potentiometer wire, and l = length at which the null point is obtained . This ratio `(l)/(L)` is NATURALLY very accurate if both l and L are sufficiently large. So, a long wire is used in a potentiometer experiment. l = 250 cm = 2.5 cm , L = 4m , emf of the potentiometer cell, `E_(0)`= 2V So. the emf of the second cell = ` (l)/(L)E_(0) = (2.5)/(4) xx 2 = 1.25`V |
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| 38099. |
Two long straight conductors are connected radially to two arbitary points A and B of a circular conductor. Calculate the magnetic field at the center of the coil. |
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Answer» |
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| 38100. |
What is meant by communication and what are differntmeans? |
| Answer» Solution :Communication refers to the transmission of information or message from ONE POINT to another point where it reaches faithfully in an intelligible FORM. EXAMPLES of different means of communication are Telephone, TV, redio and satellite communications. | |