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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.
| 42801. |
A man of mass 62 kg is standing on a stationary boat of mass 238 kg. The man is carrying a sphere of mass 0.5 kg in his hands. If the man throws the sphere horizontally with a velocity of 12 ms^(-1), find the velocity with which the boat will move (in magnitude) |
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Answer» `0.02 MS^(-1)` |
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| 42802. |
State Right hand thumb rule. |
| Answer» Solution :If we curl FINGERS of RIGHT hand in the direction of current in the LOOP, then the stretched THUMB gives the direction of the magnetic moment associated with the loop. | |
| 42803. |
A parallel plate capacitor has plate area A and separation between the plates equal to d. A material of dielectric constant K and resistivity rho is filled between the plates. The switch is closed to connect the capac- itor to a cell of emf V. (a) Write the steady state current in the circuit and charge on the capacitor. (b) When the circuit is in steady state, switch s is opened (at t = 0). Write charge on the capacitor as function of time (t) after this |
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Answer» (b) `q=(K in_(0)AV)/(d)E^(-(t)/(K rhoin_(0)))` |
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| 42804. |
A solenoid is 2m long and 4 cm in diameter. It has 4 layers of windings of 1000 turns each and carries a current of 5A. What is the magnetic field at the centre of the solenoid ? |
| Answer» SOLUTION :`n=N/l=(1000xx4)/2=2000 B=mu_0nI=4pixx10^-7xx2000xx5=4pixx10^-3T` | |
| 42805. |
Which colour of light travels with maximum velocity in a medium/ |
| Answer» SOLUTION :Dispersion is the splitting of WHITE light into it.s constituent COLOURS after PASSING through a PRISM. | |
| 42806. |
Four identical conducting rods are connected by pins. The velocity of point R is v. A uniform magnetic field B acts out of the paper. Choose the correct statement(s). (PQ=PS=4l and QR=SR=3l) |
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Answer» The motional EMF across `PQ` is `(6Blv)/(5)` Force `=mv(DV)/(dx)` |
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| 42807. |
Maximum uncertainty in position of a proton is6xx10^(-8)m .Uncertainty in measurement of its velocity will be …….(h=6.625xx10^(-34))Js,Mass of proton =1.67xx10^(-27) kg |
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Answer» `1mms^(-1)` Uncertainty in momentum `Deltap=(h)/(2piDeltax)` `THEREFORE Deltap=(6.625xx10^(-34))/(2xx3.14xx6xx10^(-8))` `therefore Deltap=0.1758xx10^(-26)` `therefore mDeltav=0.1758xx10^(-26)` `therefore Deltap=(0.1758xx10^(-26))/(m)` `=(0,1758xx10^(-26))/(1.67xx10^(-27))=0.105269xx10^(1)` Uncertainty in velocity `therefore Deltav~~1.0 ms^(-1)` |
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| 42808. |
A hollow sphere of mass m and radius 'r' is rotating with velocity omega. It suddenly stops and 75% of K.E. is converted into heat. If its specific heat is 's' J/kg/K, the rise of temperature is : |
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Answer» `(R^(2)omega^(2))/(4s)` `(75)/(100)XX(1)/(2)xx(2)/(3)MR^(2)omega^(2)=msthetaortheta=(R^(2)omega^(2))/(4s)` |
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| 42809. |
In the diagram XY is a long solenoid of insulated wire wound on a cardboard tube. PQ is a soft iron cylinder. The current is flowing in the wounded wire in the direction shown in figure. For this arrangement mark the correct statement. |
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Answer» X : North , Y : South , P : North |
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| 42810. |
The diagram, given below, shows the refracton of a plane wavefront, incident on the surface PP' separating two media, (1) and (2). Which of the media is the rarer one ? |
| Answer» Solution :MEDIUM `2` is RARER medium and medium `1` is DENSER medium. | |
| 42811. |
It is possible for two lenses to produce zero power? |
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Answer» SOLUTION :Yes. It is possible for two lenses to produce zero POWER, Both the SURFACES of lenses are EQUALLY curved. i.e. `R_(1) = R_(2)` and hence Power(p) ` = (MU - 1) ((1)/(R_(1))-(1)/(R_(2)))=0` |
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| 42812. |
What is NAND gate? Write its symbol, truth table and Boolean equation. |
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Answer» Solution :NAND gate is constructed using the COMBINATION of AND gate and the NOT gate. `therefore AND +NOT = NAND` This is an AND gate follows by a NOT gate.  The symbol of this gate is shown as in figure (a). The gate have two input and one output. The truth table of NAND gate is shown in table (b).  Function of NAND gate: The output is EQUAL to .1. when any one input is equal to .0. and the output is equal to .0. when all the inputs are equal to .0.. The BOOLEAN equation of NAND gate is `Y=bar(A*B)` and it is read as "Y is equal to NOT A and B". NAND gates are also called universal gates since by using the gates you can realise other basic gates like OR, AND and NOT. |
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| 42813. |
Closed organ pipe produce resonance with sound wave of wavelength 1.2m has length of air column |
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Answer» 30cm |
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| 42814. |
If tube length of astronomical telescope is 105cm and magnifying power is 20 for normal setting, the focal length of the objective is |
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Answer» `100 CM` |
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| 42815. |
Statement-1: Assuming zero potential at infinity, the gravitational potential at a point can never be positive. Statement-2: The magnitude of gravitational force between two particles has inverse square dependence on the distance between two particles. |
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Answer» Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1. |
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| 42816. |
Assertion : Unlike electric force and gravitational forces, nuclear force has limited range. Reason : Nuclear force do not obey inverse square law. |
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Answer» If both ASSERTION and reason are TRUE and reason is the CORRECT explanation of assertion. |
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| 42817. |
Find the de-Broglie wavelength of an electron with kinetic energy of 120 eV. |
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Answer» SOLUTION :`lambda=(H)/(sqrt(2mE))` `=(6.625 XX 10^(-34))/(sqrt(2 xx 9.1 xx 10^(31) xx 120 xx 1.6 xx 10^(-19)))` `=1.121 xx 10^(-10)`m. |
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| 42818. |
A straight rod OABCD is strapped on to the end of a straight hose pipe H with 'A' at the nozzle of the pipe (figure). Strings are ties to the rod at B,C and D and are allowed to drop down vertically. The lengths of the strings at B, C and D to just touch the stream of water, streaming out of the hose pipe from its nozzle, are in the ratio |
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Answer» `(1)/(AB):(1)/(BC):(1)/(CD)` `l=(1)/(2)GT^(2)=(1)/(2)g((Ax)/(v))^(2)` `l_(1):l_(2):l_(3)=AB^(2):AC^(2):AD^(2)` |
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| 42819. |
What is earth's atmosphere? |
| Answer» Solution :The GASEOUS envelope SURROUNDING the earth is CALLED earth.s ATMOSPHERE. | |
| 42820. |
A person wants a real image of his own, 3 times enlarged. Where should be stand infront of a concave mirror of radius of curvature 30 cm ? |
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Answer» 30 cm `(1)/(3u) + (1)/(u) = (-1)/(15)` `(1)/(u) ((4)/(3)) = (-1)/(15)` `60 = - 3u rArr u = - 20 cm`. |
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| 42821. |
A conductor is moved in a direction parallel to unifrom magnetic field. Will an induced current develop in a conductor? |
| Answer» Solution :No, because in this case Lorentz FORCE on the FREE electrons in the conductor is zero. Therefore, no P.D. CREATED ACROSS the conductor. | |
| 42822. |
Two blocks of masses m and 3m on a horizontal surface are in contact with the ends of a horizontal massless spring. The coefficient of friction between m and surface and between 3m and surface is mu and mu//3 respectively. The two blocks are moved towards each other to compress the spring and then released. The two blocks move off in opposite directions covering distances S_1 and S_2 before comming to rest. S_1 : S_2 is |
| Answer» ANSWER :C | |
| 42823. |
Two small magnetseach of magnetic moment M_(0)is placed parallelto each other the magneticfield at point O is |
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Answer» `zero ` `B=(mu_(0)M_(0))/(4pir^(3))`  `B_(1)=B_(2)=(mu_(0)M_(0))/(4pir^(3))` `therefore B=B_(1)-B_(2)=0` |
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| 42824. |
In which case are the electric field lines parallel to one another? |
| Answer» SOLUTION :For a UNIFORM ELECTRIC FIELD. | |
| 42825. |
When a stationary wave is formed then the particles of the medium- |
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Answer» Are at rest |
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| 42826. |
Discuss amplitude modulation |
| Answer» Solution :AMPLITUDE modulation is the process in which the amplitude of the HIGH frequency CARRIER wave changes in ACCORDANCE with the amplitude of the audio signal. | |
| 42827. |
A box is placed on an inclined plane and has to be pushed down. The angle of inclination |
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Answer» EQUAL to ANGLE of friction |
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| 42828. |
Two different coils have self- inductances L_(1) = 16 mH and L_(2)= 12mH. At a certain instant, the current in the two coils is increasing at the same rate and power supplied to the two coils is the same. Find the ratio of i) induced voltage ii) current it) energy stored in the two coils at that instant. |
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Answer» SOLUTION :i) `V_(1)=L_(1)(dI)/(DT), V_(2)=L_(2)(dI)/(dt)` `(V_(1))/(V_(2))=(L_(1))/(L_(2))=(16)/(12)=(4)/(3)` ii) `P=V_(1)I_(1)=V_(2)I_(2) implies (I_(1))/(I_(2))=(V_(1))/(V_(2))=(3)/(4)` iii) `(U_(1))/(U_(2))=((1)/(2)L_(1)I_(1)^(2))/((1)/(2)L_(2)I_(2)^(2))=((L_(1))/(L_(2)))((I_(1))/(I_(2)))^(2)=(4)/(3)((3)/(4))^(2)=(3)/(4)` |
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| 42829. |
Monochromatic light of frequency 6.0 xx 10^14 Hz is produced by a laser. The power emitted is 2.0 xx 10^(-3) w. |
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Answer» SOLUTION :ENERGY of each PHOTON `E=hv=6.63 xx10^-34xx6.0xx10^14 = 3.98 XX 10^-19 J` |
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| 42830. |
Water falls from a tap, down the streamline |
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Answer» a)AREA decreases |
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| 42831. |
A lens has focal length f. It gives diffraction pattern of Fraunhoffer type of a slit giving width of w. If the wavelenth of light used is lambda, then what is the distance of first dark band and next bright band from axis? |
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Answer» `(a)/(lambda)F` n = 1 `sin theta = (lambda)/(omega)` `Rightarrow theta = (lambda)/(omega)` If distance of FIRST dark fringe is x, then `theta = (x)/(f)`. So, `(x)/(f) = (lambda)/(a), x = (lambda)/(a)f`. |
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| 42832. |
According to Joule's law, if the potential difference across a conductor having a material of specific resistance p remains constant, then the heat produced in the conductor is directly proportional |
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Answer» `RHO` |
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| 42833. |
The ground state energy of hydrogen atom is –13.6 eV. What are the kinetic and potential energies of the electron in this state? |
| Answer» SOLUTION :13.6 EV , - 27.2 eV | |
| 42834. |
A string of neglisible mass going over a clamped pulley of mass m supports a block of mass M as shown in figure. Find the force on the pulley by the clamp. |
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Answer» |
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| 42835. |
In a mercury in glass thermometer the cross section of the capillary is A_(0) and volume of the bulb is V_(0) at 0^(@)C. If mercury just fills the bulb at 0^(@)C, find the that the length of mercury in the capillary at temperature t.^(@)C. Given that beta=coefficient of cubical, expansion on mercury and alpha= coefficient of linear expansion of glass. |
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Answer» |
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| 42836. |
When a comb rubbed with dry hair attracts pieces of paper. This is because the |
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Answer» comb polarizes the piece of paper |
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| 42837. |
If hat(i) denotes a unit vector along incident light ray hat( r) a unit vector along refracted ray a medium of refractive index mu and hat(n) vector normal to boundary of medium directed towards incident medium, then law of refraction is |
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Answer» `HAT(i),hat(N)=MU(hat(r).hat(n))` |
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| 42838. |
A galvanometer needs 50mV for full scale deflection of 50 Divisions. Find it voltage sensitivity. What must be its resistance if its current sensitivity is 1 Div/A. |
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Answer» Solution :`V_s = (theta)/(V) = (50"Div")/(50mv)= 10^3` div/v`I_s to` CURRENT sensitivity `R_(g) = (I_s)/(V_s) = 10^(-3)w``V_s to` VOLTAGE sensitivity |
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| 42839. |
A metal aeroplane having a distance of 50 meter between the tips of its wings is flying horizontally with a speed of 360 km/hours. At the place of flight , the earth's total magnetic field is 4. 0xx10^(-5) W//m^(2) and the agnle of dip is 30^(@). Find out the induced potential difference between the tips of its wings . If a bulb is connected across the edges of the wings ,will it light up ? |
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Answer» 0.1 VOLT, BULB will be LIGHT up . |
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| 42840. |
Which of the following would increase the capacitance of a parallel-plate capacitor? |
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Answer» Using smaller plates |
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| 42841. |
The ratio of size of a hydrogen atom to the size of its nucleus is |
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Answer» `10^(5)` |
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| 42842. |
The optical path difference between two identical waves arriving at a point is 371 lambda. Then the point : |
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Answer» is DARK |
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| 42843. |
Assertion (A) The magnetic moment (mu) of an electron revolving around the nucleus decreases with increasing principle quantum number (n).Reason (R ) Magnetic moment of the revolving electron , muprop n. |
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Answer» If both ASSERTION and REASON are TRUE and Reason is CORRECT EXPLANATION of Assertion. |
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| 42844. |
When a metallic plate swings between the poles of a magnet |
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Answer» no EFFECT on the plate |
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| 42845. |
A magnetic field set up using Helmholtz coils (described in Exercise 4.16) is uniform in a small region and has a magnitude of 0.75 T. In the same region, a uniform electrostatic field is maintained in a direction normal to the common axis of the coils. A narrow beam of (single species) charged particles all accelerated through 15 kV enters this region in a direction perpendicular to both the axis of the coils and the electrostatic field. If the beam remains undeflected when the electrostatic field is 9.0xx10^(-5)Vm^(-1), make a simple guess as to what the beam contains. Why is the answer not unique ? |
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Answer» Solution :1. Here, velocity of charged particle is `vecv _|_vecE _|_vecB`. In this situation, for an extremely thin beam ofcharged PARTICLES to pass undeflected through a given region of electric and magnetic FIELD, speed of each particle should be, `v=E/B=(9xx10^(5))/0.75=1.2xx10^(6)m/s` 2. Now, kinetic energy gained by above particle while passing through a potential DIFFERENCE V is, `1/2mV^(2)=Vq` `thereforeq/m=v^(2)/(2V)` `thereforeq/m=(1.2xx10^(6))/((2)(15xx10^(3)))` `thereforeq/m=4.8xx10^(7)C/(kg)` 3. Here charged particles in the given beam may be deuterons because for deuterons `(""_(1)H^(2))`, `("charge")/("mass")=e/(2m_(p))` (`because` Deuteron in the nucleus which contains one proton and one neutron) = `(1.6xx10^(-19))/(2xx1.67xx10^(-27))` = `4.79xx10^(7)C/(kg)` = `4.8xx10^(7)C/(kg)""...(1)` (4) Above answer is not the only answer (or unique answer) because here the charged particles may be, (i) `He^(+2)` ions for which `("charge")/("mass")=(2e)/(4m_(p))=e/(2m_(p))` (II) `Li^(+3)` ions for which `("charge")/("mass")=(3e)/(6m_(p))=e/(2m_(p))` (iii) `Be^(+4)` ions for which `"charge"/"mass"` = `(4e)/(8m_(p))=e/(2m_(p))` Answer obtained in equation (1) is not the unique answer. |
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| 42846. |
A transformer is an electrial device which is used for changing the a.c. voltages. It is based on the principle of mutual induction, i.e., whenever the amount of magnetic flux linked with a coil changes, an e.m.f. is induced in the neighbouring coil. For an ideal transformer, (E_(s))/(E_(P)) = (I_(P))/(I_(s)) = (n_(s))/(n_(P)) where the symbols have their usual meaning Read the above passage adn answer the following question : (i) A transformer has 20 turns in primary and 200 turns in seconday. If the primary is connected to 220 V d.c. supply, what will be the voltage across secondary ? (ii) The output voltage of an ideal tansformer connected to 240 V a.c. mains is 24 V. When this transformer is used to light a bulb with rating 24 V, 24 W, what is thr primary current ? (iii) What values of life do you learn from the theory of transformer ? |
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Answer» Solution :(I) Here, `n_(p) = 20, n_(s) = 200, E_(p) = 220 V d.c., E_(s) = ?` Voltage acorss seconday will be zero, as transformer does not work on d.c. It is based on mutual induction. (ii) Here, `E_(p)= 240 V, E_(s) = 24 v, I_(s) = (P_(0))/(E_(s)) = (24)/(24) = 1 A, I_(p) = ?` From `(E_(s))/(E_(P)) = (I_(P))/(I_(s)) , I_(P) = (E_(s) xx I_(s))/(E_(P)) = (24 xx 1)/(240) = 0.1 A` (iii) The relation `(E_(s))/(E_(P)) = (I_(P))/(I_(s))` show that for a step up transformer , `E_(s) gt E_(P) :. I_(P) gt I_(s)` or `I_(s) lt I_(P)` i.e., when a transformer raises the a.c. voltage, ALTERNATING current reduces in the same ratio. For example, if a.c. voltage becomes 100 times, output alternating current becomes `(1)/(100)` time. In day to day life, we find that you cannot gain on all fronts, neither you will lose on all fronts. The gains and losses go together. Gain of one is loss of the other. In life, you have to weigh your priorities and act to meet them KEEPING in ming the above principle. |
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| 42847. |
IDENTIFY THE CORRECT SPELLING: |
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Answer» COMMUNICATION |
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| 42848. |
A coll of resistance 10Omegaand inductance 5 H is connected at a 100 V battery. Then the energy stored in the coil is |
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Answer» 250 J ` I = V/R = (100 V)/( 10 Omega) = 10 A ` Energy stored = `1/2LI^(2)= 1/2 XX 5(10)^(2)= 250 j` |
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| 42849. |
The ABC is a triangular plate of uniform thickness. The sides are in the ratio shown in the figure. I_(AB) , I_(BC) and l_(CA) are the moments of inertia of the plate about AB, BC and CA respectively. Which one of the following relation is correct? |
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Answer» `I_(AB)+I_(BC)=I_(CA)`  Therefore `I_(BC)gtI_(AB)gtI_(AC)` or `I_(BC)gtI_(AB)` |
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| 42850. |
The ratio of loss of heat from a metal sphere at 327^(@)C to that of the same sphere at 527^(@)C. When placed in the surrounding of temperature 127^(@)C is |
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Answer» `(1)/(2)` |
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