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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.
| 43801. |
How does resolving power of a telescope change in decresing the aperture of its objective lens ? Justify your answer. |
| Answer» Solution :As resolving power of a TELESCOPE`=(A)/(1.22lamda)`, hence on DECREASING the aperture A of its objective LENS, resolving power of telescope DECREASES in the same RATIO. | |
| 43802. |
When the light is reflected from the surface of the mirror, its speed and wavelength will : |
| Answer» Answer :A | |
| 43803. |
A 100 kg satellite circles Earth once every 4 h in an orbit having a radius of 8000 km. Assuming that Bohr's angular momentum postulate applies to satellite just as it does to an electron in the hydrogen atom, find the quantum number of the orbit of the satellite. |
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Answer» |
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| 43804. |
Value of charge on a body which carries 10 excess electrons is ………….. |
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Answer» `1.6xx10^(18) C` |
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| 43805. |
The word 'Magnetism' was derived from Iron are __________ . |
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Answer» |
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| 43806. |
In some cases permittivity of substance turns out to be a complex or a negative quantity, and refractive index, respectively, a complex (n' = n+ ix) or an imaginary (n' = ix) quantity. Write the equation of a plane wave for both of these cases and find out the physical meaning of such refractive indices. |
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Answer» Solution :Let us write the solutions of the wave equation in the form `A = A_(0) e^(i(omegat - kx))` where `k = (2pi)/(lambda)` and `lambda` is the WAVELENGTH in the medium. If `n' = n+ ichi`, then `k = (2pi)/(lambda_(0))n'` `(lambda_(0)` is the wavelength in vaccume) and the equation BECOMES `A = A_(0) e^(chi'x) `EXP `(i(omegat_(1) - k' x))` where `chi' = (2pi)/(lambda_(0)) chi` and `k' = (2pi)/(lambda_(0)) n`. In real form, `A = A_(0) e^(chi'x) cos (omegat - k' x)` This REPRESENTS a plane wave whose amplitude diminished as it propagates to the right (privided `chi' lt 0)`. when `n' = i chi`, the similarly `A = A_(0)e^(chi' x) cos omega t` (on putting `n = 0` in the above equation). This represents a STANDING wave whose amplitude diminishes as one goes to the right (if `chi' lt 0`). The wavelength of the wave is infinite `(k' = 0`). Waves of the former type are realized inside metals as well as inside dielectrics when there is total reflection. (pentration of wave). |
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| 43807. |
Two nuclei have mass numbers in the ratio 1:8. What is the ratio of their nuclear radii? |
| Answer» SOLUTION :`R_(1)/R_(2)=[1/8]^(1/3)=1/2` | |
| 43808. |
The first line of the Paschen series in hydrogen spectrum has a wavelength of 18800 Å. The short wavelength limit of Paschen series is |
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Answer» `1215 Å` `RARR "" lambda = 18800 xx (7)/(16) = 8225 Å` |
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| 43809. |
State Bohr's quantisaiton condition of angularmomentum . Calculate theshortest wavelenghtof the Bracket series and state to whichpart ofthe electromagnetic spectrumdoes it belong . |
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Answer» Solution :For ELECTRON revolvingin astationaryorbit Bohr.squantisationcondiiton statethatthe angularmomentumis an integermultiple of `(H)/(2pi)` , wheren = 1,2,3………… The shortestwavelenghtof the Bracket series of hydrogenspectrumis given as : `(1)/(lambda) = R [(1)/((4)^(2)) - (1)/((OO)^(2))] =(R)/(16) =(1.097 xx 10^(7))/(16)` `RARR "" lambda = (16)/(1.097 xx 10^(7))= 14.59 xx 10^(7) m = 1459` nm Obviously thespectral linebelongto INFRA redregion of spectrum. |
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| 43810. |
The relation between alpha and beta is : |
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Answer» `BETA =(ALPHA)/(1+alpha)` |
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| 43811. |
If the numerical aperture of a microscope is increased then its : |
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Answer» resolving POWER is decreased |
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| 43812. |
The phase angle between the projection of U.C.M. on two mutually perpendicular diameter is, |
| Answer» ANSWER :B | |
| 43813. |
What is the magnitude of magnetic force per unit length on a wire carrying a current of 8 A and making an angle of 30^@with the direction of a uniform magnetic field of0.15 T? |
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Answer» SOLUTION :ACCORDING to Ampere.s law, `F=IlBsintheta` `thereforeF/l=IBsintheta` `thereforeF/l=(8)(0.15)sin30^(@)` `thereforeF/l=0.6Nm^(-1)` |
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| 43814. |
An air bubble is situated at a distance of 0.08 m from the centre of a sphere of radius 0.12 m. When viewed from the nearest side it appears to be distance of 0.09 m from the centre. Find the refractive index of the material of the sphere. Where will the bubble appear to be when viewed from the farther side? |
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Answer» SOLUTION :Object distance of the air bubble from `P_(1)` `-u=0.12-0.08=0.04m ` for real object. `r_(1)=0.12 m (P_(1)O)` `v=-(0.12-0.09)` i.e., `v=-0.03 m (P_(1)B)` (i) using the FORMULA`(n_(0))/(-u)+(n_(1))/(v)= (n_(0)-n_(1))/(r)` .v. is negative because it is measured opposite to the DIRECTION of incident LIGHT. `(n_(0))/(0.04)+(1)/(-0.03)=(n_(0)-1)/(0.12)` `25n_(0)-33.33=(n_(0)-1)8.33` `25n_(0)-8.33n_(0)=33.33-8.33` `16.67n_(0)-25` `therefore n_(0)=1.4997` `n_(0)=1.50`  (II) u from `P_(2)=(0.12+0.08)=0.20m` `(1.5)/(0.2)+(1)/(v)=(1.5-1)/(0.12)` `7.5+(1)/(v)=4.167` `therefore (1)/(v)=-3.333` `therefore v= -(1)/(3.333)= -(1)/(10//3)` or `v=(-3)/(10)=-0.30m` |
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| 43815. |
Which source is associated with a line emission spectrum |
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Answer» ELECTRIC fire |
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| 43816. |
A proton beam has a circular cross sectional area A and it carries a current I distributed uniformly over its cross section. Calculate the magnetic energy per unit length of the beam within the beam. |
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Answer» |
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| 43817. |
For sky wave propagation of a 10 MHz signal, what should be minimum electron density in the ionosphere? |
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Answer» `-1.2xx10^12m^-3` |
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| 43818. |
The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will be |
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Answer» 2R |
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| 43819. |
The P-V diagram for a cyclic process is a triangle ABC drawn in order. The co-ordinates of A, B, C are (4, 1), (2, 4) & (2, 1). The co-ordinates are in order of P - V in which P is in N//m^(2) & volume in litres. The work done during the process from A to B is : |
| Answer» Answer :D | |
| 43820. |
Use of eddy currents is done in the following except |
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Answer» Moving COIL galvanometer |
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| 43821. |
A small metallic sphere carrying charge +Q is located at the centre of a spherical cavity in a large uncharged metallic spherical shell. Write the charge on the inner and outer surface of the shell. Write the expression for the electric field at the point? |
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Answer» Solution :As shown in the adjoining CHARGE -Q is induced on the inner surface of the metallic shell and, in turn, a charge +QIS induced on the outer surface of the shell. The electric field at point `P_1` situated in the cavity at a distance r from the centre of charged small metallic sphere is ` oversetto E=(1)/(4 pi in _0) .(Q)/(r^(2)) hatr ` The field is solely due to charge +Q of small metallic sphere and there is no field due to CHARGES induced on the hollow metallic shell. 
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| 43822. |
Cellular Mobile radio works on the frequency range is |
| Answer» Answer :A | |
| 43823. |
The wavelength associated with electrons on acceleration is generally of the order of "_____________" metres. |
| Answer» Answer :A | |
| 43824. |
A proton and an alpha-particle start from rest in a uniform electric field, then the ratio of times of flight to travel same distance in the field is |
| Answer» Answer :D | |
| 43825. |
A fish looking up through the water see the outside world, contained in a circular horizon. If the refraction index of water is (4)/(3) and the fish is 12 cm below the water surface, then the radius of this circle in cm is |
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Answer» `39sqrt(7)` |
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| 43826. |
A particle moves according to the law given below where x, v and a are displacement,velocity and acceleration respectively and omega, A are + ve constant then match the following. |
| Answer» Solution :`A RARR (p, Q, R, s), (B) rarr (r, s) , (C ) rarr (p, q , r, s) , (D) rarr (p, q , r, s)` | |
| 43827. |
An LCR circuit is equivalent to a damped pendulum In an LCR circuit the capacitor is charged to Q_(0) and then connected to the L and R as shown below : Thus potential energy stored in the capacitor and that in the inductor also oscillates between maximum value an zero with double the frequency. If a student plots graphs of the square of maximum charge (Q_("max")^(2)) on the capacitor with time (t) for two different values L_(1) and L_(2) (L_(1) gt L_(2)) of L then which of the following reprersent this graph correctly ? (Plots are shematic and not drawn to scale ) |
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Answer»
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| 43828. |
Which of the following is false regarding significant figures ? |
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Answer» All non - zero digits are significant. |
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| 43829. |
A bove curie temp |
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Answer» a paramagnetic SUBSTANCE BECOMES FERRO magnetic |
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| 43830. |
The ratio of the weight of the man in stationary lift and in a life accelerating downwards with uniform acceleration is 3:2. The acceleration of the lift is : |
| Answer» ANSWER :A | |
| 43831. |
Which of the following mirror is used by a dentist to examine a small cavity? |
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Answer» Concave mirror |
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| 43832. |
Atomic mass of ._6^13C is 13.00335 amu and its mass number is 13.0. If 1 amu = 931 MeV. binding energy of the neutrons present in the nucleus is |
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Answer» 0.24 MeV |
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| 43833. |
A ray of light is incident on the face AB of a glass prism ABC having the vertex angle A equal to 30^@. The face AC is silvered and a ray of light incident on the face AB retraces its path. If the refractive index of the material of prism is sqrt3 find the angle of incidence on the face AB. |
| Answer» ANSWER :A | |
| 43834. |
Six wires, each of resistance r, are connected so as to form a tetrahedron. The equivalent resistance of the combination when current enters through one corner and leaves through some other corner is |
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Answer» r ` (##MTG_WB_JEE_PHY_C13_E02_009_S01.png" width="80%"> The equivalentresistancer.AcrossAB isgivenby `(1)/(r. ) = (1)/( 2r) +(1 )/( 2r )+1/r=4/(2 r)ORR.= r/2` |
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| 43835. |
An object is placed at the focus of concave mirror of focal length 20 cm . The distance of the image is : |
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Answer» 10 cm |
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| 43836. |
The acceleration due to gravity at a distance x from the centre of earth is 8ms^(-2). The earth shrinks in radius by 5% but its mass remains constant. The acceleration due to gravityat a disatance 'x' from the centre of earth now is: |
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Answer» `7ms^(-2)` `therefore ` The value of g will not change. Thus correct choice is (b). |
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| 43837. |
Find the Equivalent resistance across A and R in the given circuit if r=10Omega, R=20Omega. |
Answer» SOLUTION : In unbalanced wheastone.s bridge as shown the EFFECTIVE resistance between A and B is `R_(AB)=r[(3R+r)/(3r+R)]rArr R_(AB)=14Omega` |
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| 43838. |
A capacitor in an LC oscillation has a maximum potential difference of 1.5 anda maximum energy 360muJ. At a certain instant t=t_(0), the potential difference across the capacitor is V volt? |
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Answer» The VALUE of CAPACITANCE is |
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| 43839. |
T_(1//2) for a radioactive nuclei is 12.5 hr. and its mass is 256 gm. The time after which an amount of the remaining substance is 1 gm is ___ hr. |
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Answer» 75 |
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| 43840. |
Light of 600 nm incidents on an obstacle a it diffracts very less upto 15 m, then find line dimension of obstacle. |
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Answer» 3 mm `Z_(F)=(a^(2))/(lambda)` `:.a=sqrt(Z_(f)lambda)` `= sqrt(1500xx6xx10^(-5))` `=sqrt(9000xx10^(-5))` `=sqrt(9x10^(-2))=3xx10^(-1) cm=3 mm` |
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| 43841. |
Which of the following is known as Hinsberg reagent ? |
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Answer» `COOH-COOH` |
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| 43842. |
अधिकतर पेड़-पौधे होते है |
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Answer» स्वपोषी |
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| 43843. |
The magnetic induction and magnetising field intensity in a sample of magnetic material are B and H respectively . The magnetic susceptibility of the material is |
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Answer» `(B)/(mu_(0)H)` |
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| 43844. |
For a transistor beta=40 and I_(B)=25muA .Find the value of I_(E) |
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Answer» Solution :`beta=((deltaI_(C))/(deltaI_(B)))_(C_(CE))`(if only d.c values are considered) `therefore I_(C)=betaI_(B)=40xx25xx10^(-6)=1000xx10^(-6)A` `therefore I_(E)=I_(B)+I_(C)=(25xx10^(-6)+1000xx10^(-6))amp` |
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| 43845. |
The energy flux of sunlight reaching the surface of the earth is 1.388xx103W//m^(2). How many photons (nearly) per square metre are incident on the Earth per second ? Assume that the photons in the sunlight have an average wavelength of 550 nm. |
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Answer» `2xx10^(10)` ENERGY flux `phi=1.388xx10^(3)Wm^(-2)` ALSO, `h=6.626xx10^(-34)Js` and `c=3xx10^(8) ms^(-1)` `:.` energy of each photon `E=(hc)/(lambda)` `=(6.626xx10^(-34)xx3xx10^(8))/(550xx10^(-9))` `=6.31xx10^(-19)J` `:.` no. of photons per square metere of earth `=(phi)/(E)=(1.388xx10^(3))/(3.61xx10^(-19))=3.85xx10^(21)` |
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| 43846. |
The mathematical form of Guass's law can be expressed as. |
| Answer» SOLUTION :`OINT E.ds = q/epsilon_0` | |
| 43847. |
Two concentric hollow conducting spheres of radius r and R are shown. The charge on outer shell is Q. what charge should be given to inner sphere so that the potential at any point P outside the outer sphere is zero ? |
| Answer» Answer :C | |
| 43848. |
A space vehicle of 1 tonne mass is to take off from the Moon and fly to the Earth. Find the amount of fuel required. Compare the result with the amount of fuel needed to send an identical vehicle from the Earth. Assume the rocket to be a single-stage vehicle. |
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Answer» |
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| 43849. |
A 1000 kg elevator rises from rest in the basement to the fourthfloor,a distance of 20 m. Asit passes the fourth floorits speedis4 m s^(-1) . There is a constantfrictionalforceof 500 N. The workdoneby the liftingmechanism is |
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Answer» `196 XX 10^(3)`J ` 1000 xx 9.8 xx 20 = 196 xx 10^(3) J ` Work done to impartvelocityto the body = `1/2 mv^(2)` ` 1/2 xx 10^(3) xx 16 =8 xx 10^(3)J` WORKDONE against frictional force ` 500 xx 20= 10 xx10^(3) J` Totalworkdone = ` 214 xx 10^(3) J` |
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| 43850. |
Which of the given phenomenon is based on the fact that light waves are transverse electromagnetic waves? |
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Answer» Diffraction |
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