45406 + Interview Questions in Physics in Class 12

1.	Two bombs of 10 and 15 kg are thrown from acanon with the same velocity in in the same direction. Which bomb will reach the ground first ?
Answer» Solution :both will reach SIMULTANEOUSLY becouse the TIME of flight does not depend on the mass (if AIR RESISTANCE is NEGLIGIBLE)

Discussion

2.	What type of group we expect between V and I in an ohmic conductor ?
Answer» SOLUTION :STRAIGHT

Discussion

3.	When a plastic rod rubbed with wool is brought near the knob of a negatively charged gold leaf electroscope, the gold leaves
Answer» CONTRACT Dilate Start OSCILLATING COLLAPSE completely Answer :B

Discussion

4.	A coolie lifts a box and walks on horizontal smooth surface, the work done by him against gravity is :
Answer» ZERO Product of weight and distance travelled Product of weight and HEIGHT of the box None of these Solution :Work done is zero as force and displacement are perpendicular to each other.

Discussion

5.	An LCRseries circuit has a resistance of 25 Omega and a reactance of 93.25 Omega. If the reactance is capacitive, what is the phase angle between the current and applied emf ? Does the applied emf lag behind or lead the current ?
Answer» Solution :Date : ` R = 25 Omega, \|X_(L) - X_(C)\| = 93.25 Omega` (capacitive) Since the reactance is capacitive , ` X_(C) gt X_(L)` The phase angle ` phi ` is geven by ` tan phi = (X_(L) - X_(C))/R = (-93.25)/25` ` = - 3.730` ` :. Phi = tan ^(-1) (- 3.730)` ` = -75^(@)` `{:(log 93.25,," "1.9696),(log 25,,ul(-1.3979)),(,," "0.5717):}` AL ` 0.5717 = 3.730` i.e. the applied emf lags BEHIND the current by ` 75^(@)`.

Discussion

6.	(A): There may be an induced emf in a loop without induced current (R): Induced current depends on the resistance of the loop
Answer» Both A and R are true and R is the correct EXPLANATION Both A and R are true but R is not the correct explanation of A A is true but R is false Both A and R are false Answer :A

Discussion

7.	Match the column I with column II.
Answer» ANSWER :A::B::C::D

Discussion

8.	Why are elemental dopantsfor Silicon on Germanium usually chosen from group XIII on group XV ?
Answer» Solution :While preparing N or P type semiconductor from pure semiconductor, size of impurity atoms should be nearly equal to the size of SI or GE atoms (so that SYMMENTRY of crystalline structure, would be maintained before and after the doping.) Also, the type of impurity atoms should be such that after its bonding through covalent bonds with the host crystal, we should GET required free charge carriers. Above conditions are fulfilled by elements in `13^(th)` and `15^(th)` group (XIII and XVth group) and so they are SELECTED for preparing N and P type semiconductors.

Discussion

9.	Static charge is a source of………………..but nor of…………….. .
Answer» ANSWER :ELECTRIC FIELD ; MAGNETIC field,

Discussion

10.	State the nature and any four properties of alpha-particle.
Answer» Solution :Nature of `alpha`-particles (1) An alpha particle is a helium NUCLEUS, i.e., a doubly ionized helium atom. It consists of two protons and two neutrons. (2) Mass of the `alpha cong 4u` Charge on the `alpha-"particle"=2 xx "charge on the PROTON"` Properties of `alpha`-particles : (1) Of the three types of radioactive radiations, `alpha`-particles have the maximum ionising power. It is about 100 times that of `BETA`-particles and `10^(4)` times that of `gamma`-rays. (2) They are deflected by electric and magnetic fields since they are charged particles. Their deflection is less than that of B-particles in the same field. (3) They affect photographic plates. (4) They cause fluorescence in fluorescent materials such as zincsulphide. (5) They emerge from the nuclei with TREMENDOUS speeds in the range of `(1)/(100)`th to `(1)/(10)`th of the speed of light in free space.

Discussion

11.	Which is the most unstable elementary particle in an atom?
Answer» Solution :Neutron is the most UNSTABLE elementary in an ATOM. It decays into PROTON, ELECTRON and antineutrino.

Discussion

12.	A radio can tune to any station to 7.3MHz to 12 MHz band. The corresponding wavelength band is
Answer» 25m-40m 10m-30m 20-40m 25m-35m Solution :WAVELENGTH corresponding to 7.5 MHz FREQUENCY `lambda_(2)=(c)/(v)=(3xx10^(8))/(12xx10^(8))=25m` Corresponding to the given frequency bands, the wavelength band is 25m-40m.

Discussion

13.	Select the correct statement : (Only force on a particle is due to electric field)
Answer» A CHARGED particle moves along the electric LINE of force. A charged particle may MOVE along the line of force A charged particle never moves along the line of force A charged particle moves along the line of force only if relased from rest. ANSWER :B

Discussion

14.	A signal emitted by an antenna from a certain point can be received at another point of the surface in the form of
Answer» Sky wave GROUND wave Sea wave Both (a) and (b). Solution :Ground wave and sky wave both are AMPLITUDE modulated wave and the amplitude modulated signal is TRANSMITTED by a TRANSMITTING ANTENNA and received by the receiving antenna at a distance place.

Discussion

15.	A straight current carrying conductor is kept along the axis of circular loop carrying current . The force exerted by the straight conductor on the loop is …… .
Answer» PERPENDICULAR to the PLANE of the loop in the plane of the loop , AWAY from the CENTER in the plane of the loop , towards the center zero Solution :d

Discussion

16.	For a radio signal to travel 150 km from the transmitter to a receiving antenna, it takes
Answer» `5xx10^(-4)` second `4.5xx10^(-3)` second `5xx10^(-8)` second `4.5xx10^(-6)` second Solution :`t=(s)/(V)=(150xx10^(3)m)/(3XX10^(8)MS^(-1))=5xx10^(-4)s`

Discussion

17.	Given the mass of iron nucleus as 55.85 u and A = 56, find the nuclear density. (u = 1.67 xx 10 ^(-27) kg, r = 1.2 xx 10 ^(-15)m )
Answer» SOLUTION :`rho = M/C = (55.85 XX 1.6603 xx 10^(-27))/(4/3 xx pi xx (1.2 xx 10^(-15))^(3)) xx 1/56 = 2.29 xx 10^(17) kgm^(-3)`

Discussion

18.	The sun appears to be elliptical during sunset. What is the reason behind it?
Answer» ANSWER :REFRACTION of LIGHT

Discussion

19.	A flyover bridge is in the form of a circular arc of radius 39.5m. What is the limiting speed at which a car can cross the bridge without loosing contact with the road, at the highest point ? (Assume that centre of gravity of the car is 0.5 m above the road and g = 10 m/s^2 ).
Answer» SOLUTION :Since the centre of gravity of the car is 0.5 m above the ROAD, the effictive RADIUS 39.5 + 0.5 =40 m `THEREFORE` For equilibrium (mv^2)/r=mg thereforev^2=rg `V=SQRT(rg)=sqrt(40xx10)=20` m/s.

Discussion

20.	A rectangular coil of area of cross-section is placed as shown. A magnetic field B is applied along Z-axis. The torque on the coil is
Answer» ABI along +Y-axis ABI along -Y-axis ABI along + X-axis ABI along - X-axis Solution :`VECB = B hatk` the MAGNETIC moment of coil is along X-axis and is equal to `vecM = - IAhati` `THEREFORE vectau = vecM XX vecB =-(IA)hati xx Bhatk` `vectau = - (BIA)(-hatj) = BIAhatj`

Discussion

21.	In YDSE and apparatus as shown in figure wavelength of light used in lambda. The screen is moved away from the source with a constant speed V. Initial distance between screen and plane of slits was D. Suppose P is the point where 5^("th") order maxima was lying at t = 0, then after how much time third - order maxima will lie at this point P on that screen?
Answer» `(2D)/(V)` `(2D)/(3V)` `(3D)/(2V)` `(3D)/(V)` Answer :B

Discussion

22.	Give two uses of UV rays.
Answer» SOLUTION :Uses : (i) In the analysis of the structure of ORGANIC compounds. (ii) In high RESOLVING power microscopes. (iii) In the study of bacteria.

Discussion

23.	The ill effectsassociatedwith thevariatiion of the periodof revolution of the particleina cyclotron due tothe increase of itsenergyare eleminated by slow monitoring(modulating ) the frequency of accelertingfield. Accordingto whatlaw omega (t) shouldthis frequencecy by mointoredif the masgneticinductionis equalto B and theparticleacquiresan energyDelta Wper revolution ? The charge of theparticle is q and its mass is m.
Answer» Solution :The BASIC condition is the relatistiv equaction, `(mv^(2))/(r) = Bqv`, or, `mv = (m_(0) v)/(sqrt(1 - v^(2)//c^(2))) = BQR`. Or calling, `omega = (Bq)/(m)`, we GET, `omega = (omega_(0))/(sqrt(1 + (omega_(0)^(2) r^(2))/(c^(2)))), omega_(0)= (Bq)/(m_(0)) r` is the radius of theinstantanceous orbit, The time of ACCELERATION is, `t = sum_(n = 1)^(N) (1)/(2 v_(n)) = sum_(n = 1)^(N) (pi)/(omega_(n)) = sum_(n)^(N) (pi W_(n))/(q Bc^(2))` `N` is the numbr of crossingof either `Dee`. But,n `W_(n) = m_(0) c^(2) + (n Delta W)/(2)`, therebeing two crossings of theDees per revolution. So, `t = sum (pi m_(0) c^(2))/(qB c^(2)) + sum (pi Delta W_(n))/(2q B c^(2))` `= N (Pi)/(omega_(0)) + (N (N + 1))/(4) (pi Delta W)/(qB c^(2)) = N^(2) (piDelta W)/(4 q Bc^(2)) (N gt gt 1)` Also, `r = r_(N) (v_(N))/(omega_(N)) = (c)/(pi) (del t)/(del N) = (Delta W)/(2q Bc) N` Hence finally, `omega = (omega_(0))/(sqrt(1 + (q^(2) B^(2))/(m_(0)^(2) c^(2))xx (Del W^(2))/(4 q^(2) B^(2) c^(2))) N^(2))` `= (omega_(0))/(sqrt(1 + ((Delta W)^(2))/(4 m_(0)^(2) c^(4)) xx (4 q Bc^(2))/(pi Delta W) t)) = (omega_(0))/(sqrt(1 + at))`, `a = (q B Delta W)/(pi m_(0)^(2) c^(2))`

Discussion

24.	n a Geiger-Marsden experiment, what is the distance of closest approach to the uranium nucleus of a 5.0 MeV alpha-particle before it comes momentarily to rest and reverse its direction?
Answer» ANSWER :`d=5.3xx^(-14)m`

Discussion

25.	An electron of charge e and mas m is moving in a circular path of radius r with a unifrom angular speed omega . Then which of the following statementa are correct?
Answer» The equivalent current flowing in the CIRCULAR path is proprotional to `r^(2)`. The magnetic moment due to circular current loop is independent of m. The magnetic moment due to circular current loop is EQUAL to `2e//m` times the angular momentum of the electron:The angular momentum of the particle is proportional to the areal velocity of electron. Solution :An electron moving in a circular orbit acts like a current loop. `therefore` The current flowing in the loop. `I = e/T = e/(2pi//omega)=(eomega)/(2pi)` Hence, STATEMENT (a) is incorrect. Area of the loop, `A = PIR^(2)` Magnetic moment of the loop, `M = IA= (eomega)/(2pi)PI r^(2) = (er^(2)omega)/2` Hence, statement (b) is correct. As `M = e/(2m)L` where L is the angular momentum of the electron. Hence. statement (c) is incorrect. Angular momentum `=2m(dA)/dt` where `(dA)/dt` is the area velocity. Hence, statement (d) is correct.

Discussion

26.	Find theinductance of a unitlength ofa cableconsistingof two thin-walledcoaxialmetalliccylindersif theradiusof theoutside cylinderis eta = 3.6 timesthat of the insideone. Thepermeabitityof a medium betweenthe cylinders is assumedto beequal to unity.
Answer» SOLUTION :Between the cables, where`a lt R lt b`, the magnetic field`vec(H)` satisfies `H_(varphi) 2PI r = 1` or `H_(varphi) = (I)/(2pi r)` So `B_(varphi) = (mu mu_(0) I)/(2pi r)` The associated flux per unit lengthis, `Phi = int_(r = a)^(r = b), (mu mu_(0) I)/(2pi r) xx 1 xx dr = (mu mu_(0) I)/(2pi)` In`(b)/(a)` Hence, the inductance per unit LENGTH `L_(1) = (Phi)/(I) = (mu mu_(0))/(2pi) In eta`, where `eta = (b)/(a)` We get `L_(1) = 0.26 (mu H)/(m)`

Discussion

27.	Answer the following: (a) If one of two identical slits producing interference in Young's experiment is covered with glass so thatthe lightintensity passing through it is reduced to 50%, find the ratio of the maximum and minimum intensity of the fringe in the interference pattern. (b)Whatkindof fringes do you expect to observeif white lightis used instead of monochromatic light ?
Answer» SOLUTION :After the introduction of the glass SHEET (SAY on the second slit ) . We have ` (I_2)/( I_2) =50% =(1)/(2) ` ` therefore ` Ratio of the AMPLITUDES ` = ( a_2)/(a_1)=sqrt( (1)/(2) ) =(1)/(sqrt(2)`

Discussion

28.	transverse simple harmonic wave is travelling on a string. The equation of the wave:
Answer» Is the GENERAL EQUATION for displacement of a particle of the string at any instant t Is the equation ofthe shape ofthe string at any instant t Must have sinusoidal form Is an equation ofdisplacement for the particle at any one end at a particular time t Solution :The equation of a simple harmonic wave is given as `y = A sin(omegat - kx)` This equation GIVES the displacement curve (shape ofa string in which transverse wave is propagating) as well as it gives the displacement ofa particle at POSITION x as a FUNCTION of time t.

Discussion

29.	Explain the determination of unknown resistance usingmeter bridge.
Answer» Solution :The meter bridge is another form of Wheatstone.s bridge. It consists of a uniform manganin wire AB of one meter length. This wire is stretched along a meter scale on a wooden board between two copper strips C and D. Between these two copper strips another copper strip E is mounted to enclose two gaps `G_(1) and G_(2)`. An unknown resistance P is CONNECTED in `G_(1) ` and a standard resistance Q is connected in `G_(2)`. A jockey (conducting wire) is connected to the terminal E on the CENTRAL copper strip through a galvanometer (G) and a high resistance (HR). The exact position of jockey on the wire can be read on the scale. A Lechlanche cell and a key (K) are connected across the ends of the birdge wire. The position of the jockey on the wire is adjusted so that the galvanometer shows zero deflection. Let the point be J. The lengths AJ and JB of the bridge wire now replace the resistance R and S of the Wheatstone.s bridge. Then `(P)/(Q)=(R)/(S)=(R..AJ)/(R..JB) "" ...(1) ` where R. is the resistance per unit length of wire `(P)/(Q)=(AJ)/(JB)=(l_(1))/(l_(2)) "" ...(2)` `P=Q(l_(1))/(l_(2)) ""...(3)` The bridge wire is soldered at the ends of the copper strips. Due to imperfect contact, some resistance might be introduced at the contact. These are called end resistances. This error can be eliminated, if another set of readings are taken with P and Q interchanged and the average value of Pis found. To find the specific resistance of the material of the wire in the coil P, the radius r and length `L` of the wire is measured. The specific resistanceor resistivity r can be calculated using the RELATION Resistance `=rho (l)/(A)` By rearranging the above equation, we get `rho=` Resistance `xx(A)/(l) ""...(4)` If P is the unknown resistance, equation (4) BECOMES `rho=P (pi r^(2))/(l)`

Discussion

30.	क्षेत्रफल के आधार पर भारत का सबसे बड़ा राज्य कौन सा है?
Answer» उत्तर प्रदेश मध्य प्रदेश राजस्थान बिहार Answer :C

Discussion

31.	A system consists of N_(0) nucleus at t = 0. The number of nuclei remaining after half of a half-life (that is, at time t=1/2T_(1/2))
Answer» `N_0/2` `N_0/sqrt(2)` `N_0/4` `N_0/8` ANSWER :B

Discussion

32.	x-y plane separates two media, zge0contains a medium of refractive index 1 and zle0contains a medium of refractive index 2. A ray of light is incident from first medium along a vectorhati+hatj-hatk. Find the unit vector along the refracted ray.
Answer» Solution :The law of refraction in vector form is `mu_(1)(hat(e)_(1)xxhat(N))=mu_(2)(hat(e)_(2)xxhat(n))` Here `hat(e)=(hat(i)+hat(J)-hat(k))/(sqrt(3))` `=` unit vectore along incident ray `hat(n)=hat(k)=` unit vector along normal or incidence point `:. mu_(1)(hat(e)_(1)xxhat(n))=mu_(2)(hat(e)xxhat(n))` `hat(e)_(2)=xhat(i)+yhat(j)+zhat(k)` `=` unit vectore along REFRACTED ray or `1{((hat(i)+hat(j)-hat(k))/(sqrt(3)))xxhat(k)}=2{(xhat(i)+yhat(j)+zhat(k))xxhat(k)}` or`(-hat(j)+hat(i))/(sqrt(3))=2{-xhat(I)+yhat(j)}` or `x= (1)/(2sqrt(3)), y=(1)/(2sqrt(3))` As `hat(e)_(2)` is a unit vector, THEREFORE `\|hat(e)_(2)\|=1` `RARR sqrt(x^(2)+y^(2)+z^(2))=1` or `sqrt((1/(2sqrt(3)))^(2)+((1)/(2sqrt(3)))+z^(2))=1` or ` sqrt(((1)/(12)+(1)/(12)+z^(2)))=1` or `(1)/(6)+z^(2)=1` `:. z^(2)= 1-(1)/(6)=(5)/(6)` `:. z=+-sqrt(((5)/(6)))` Since refracted ray is in negative z-axis region `:. z=-sqrt((5)/(6))` `:. hat(e)_(2)=(1)/(2sqrt(3))hat(i)+(1)/(2sqrt(3))hat(j)-sqrt(((5)/(6)))hat(k)`

Discussion

33.	For air or vacuum, K = _____ and fror all other insulating material K = _____.
Answer» SOLUTION :`1,GT1,K LT1`

Discussion

34.	यदि वस्तु की गति का पथ सरल रेखीय हो,तो ऐसी गति कहलाती है
Answer» वृत्ताकार गति विस्थापन सरल रेखीय गति इनमे से कोई नहीं Answer :C

Discussion

35.	If force on a particle vecF = (Sin at)hati + (cos at)hatj and displacement vecS = sin(frac{at}{3}hati) + cos(frac{at}{3})hatj are functions of time (t) then value of t at which they are perpendicular for first time is (a is positive constant and t>0)
Answer» `t = FRAC{pi}{2]` `t=frac{3pi}{2a}` `t = frac{3pi}{4a}` `t = frac{pi}{3}` Answer :C

Discussion

36.	Which rays are not the portion of electromagnetic spectrum
Answer» X-rays Microwaves `ALPHA` -rays Radio waves Answer :C

Discussion

37.	In a stationary wave the amplitude of vibrating particle
Answer» Minimum Varies from PARTICLE to particle Zero Maximum Answer :A

Discussion

38.	According to Rutherford, the size of the nucleus is:
Answer» `10^-15`m to `10^-14`m `10^-10`m to `10^-7`m `10^-6`m to `10^-3`m `10^-3`m to `10^-1`m Answer :D

Discussion

39.	Who helped the boy out of his misery?
Answer» The doctor The mother The classmates None of the above Answer :B

Discussion

40.	Find the decay constant and the mean lifetime of Co^(55) radionuclide if its activity is known to decrease4.0% per hour. The decay product is nonradioactive.
Answer» SOLUTION :If the decay CONSTANT (in `("HOUR")^(-1)`) is `lambda`, then the ACTIVITY after one hour will decrease by a factor `E^(-lambda)`. Hence `0.96= e^(-lambda)` or `lambda= 1.11xx10^(-5)s^(-1)= 0.0408 per hour` Themeanlife time is `24.5 hour`

Discussion

41.	To draw the maximum current from a combination of cells, how should be the cells be grounded ?
Answer» Parallel SERIES Depends upon the RELATIVE values of INTERNAL and EXTERNAL resistance Mixed grouping ANSWER :C

Discussion

42.	(i) Derive an expression for drift velocity of electrons in a conductor. Hence deduce Ohm's law.(ii) A wire whose cross-sectional area is increasing linearly from its one end to the other, is connected across a battery of V volts. Which of the following quantities remain constant in the wire ?(a) drift speed (b) current density(c) electric current(d) electric field Justify your answer.
Answer» Solution :(ii) Out of four quantities given here only (c) electric CURRENT remains constant in the wire. All theremaining three quantities NAMELY : (a) drift speed, (B) current density, and (d) electric field do not remain constant because their values depend upon the cross-section area of conductorwhich is increasing linearly from one end to the other.

Discussion

43.	Three gas molecules have velocities respectively equal
Answer» `3xx10^2` m/s `4xx10^2` m/s `5xx10^2` m/s `6xx10^2` m/s Answer :A

Discussion

44.	Two plates ( area =s ) charged to + q_(1)and +q_(2)(q_(2) lt q_(1))are brought closer to form a capacitor of capacitance C. The potential difference across the plates is
Answer» `(q_(1)-q_(2))/(2C)` `(q_(1)-q_(2))/( C)` `(q_(1)-q_(2))/(4 C )` `(2(q_(1)-q_(2)))/ ( C)` SOLUTION :Answer (1) Inner plates accumulate equal and opposite charge `Q=(q_(1)-q_(2))/(2)`and that actually MAKES the capacitor Now `V=(Q)/(C )`.

Discussion

45.	The time interval observed in a frame at rest is "____________" that observed in a moving frame
Answer» LONGER than SMALLER than EQUAL to varying Answer :A

Discussion

46.	If an alpha-particle is projected normally through a uniform magnetic field, then the path of the alpha-particle inside the field will be
Answer» CIRCULAR parabolic elliptical a straight line Solution :If an `alpha`-particle is PROJECTED normally through a uniform magnetic FIELD, then the path of the `alpha` particle inside the field will be circular.

Discussion

47.	A ray of light covers distance .d. in time t, in air and distance 10 d in time t_2, in medium, then critical angle for medium is .....
Answer» `sin^(-1)((t_1)/(t_2))` `sin^(-1)((10t_1)/(t_2))` `tan^(-1)((t_1)/(t_2))` `tan^(-1)((10t_1)/(t_2))` Solution :ABSOLUTE refractive index n = `c/v` and sinC=`1/n=v/c` `therefore` sinC=`(d_m//t_2)/(d_a//t_1)` [`because d_m` and `d_a` are distances COVERED in air and medium] `thereforesinC=(d_mt_1)/(d_at_2)` `=(10d xx t_1)/(d xx t_2)` `(10t_1)/(t_2)` `therefore C=sin^(-1)((10t_1)/(t_2))`

Discussion

48.	For a L-C-R series circuit List I - with List-II (Terms have their usual meaning)
Answer» `"a"RARR"E, b"rarr"d, C"rarr"F"` `"a"rarr"f, b"rarr"e, c"rarr"d"` `"a"rarr"e, b"rarr"f, c"rarr"d"` `"a"rarr"f, b"rarr"d, c"rarr"e"` Answer :B

Discussion

49.	A +very charged body attracts a pith ball pendulum towards it Does it mean that the pith ball pendulum is nagatively charged ?
Answer» Solution :Not NECESSARILY. A +vely charged body can induce negative charge on the NEARER end of the uncharged BALL, THUS causing an attraction between the TWO.

Discussion

50.	A vessel of depth 2d cm is half filled with a liquid of refractive index mu_(1) and the upper half with a liquid of refractive mu_(2). The apparent depth of the vessel seen perpendicularly is
Answer» `d((mu_(1)mu_(2))/(mu_(1)+mu_(2)))` `d((1)/(mu_(1))+(1)/(mu_(2)))` `2D((1)/(mu_(1))+(1)/(mu_(2)))` `2d((1)/(mu_(1)mu_(2)))` Solution :(b) `H. = ((d_(1))/(mu_(1)) + (d_(2))/mu_(2)) = d((1)/(mu_(1)) + (1)/(mu_(2))).`

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Two bombs of 10 and 15 kg are thrown from acanon with the same velocity in in the same direction. Which bomb will reach the ground first ?

What type of group we expect between V and I in an ohmic conductor ?

When a plastic rod rubbed with wool is brought near the knob of a negatively charged gold leaf electroscope, the gold leaves

A coolie lifts a box and walks on horizontal smooth surface, the work done by him against gravity is :

An LCRseries circuit has a resistance of 25 Omega and a reactance of 93.25 Omega. If the reactance is capacitive, what is the phase angle between the current and applied emf ? Does the applied emf lag behind or lead the current ?

(A): There may be an induced emf in a loop without induced current (R): Induced current depends on the resistance of the loop

Match the column I with column II.

Why are elemental dopantsfor Silicon on Germanium usually chosen from group XIII on group XV ?

Static charge is a source of………………..but nor of…………….. .

State the nature and any four properties of alpha-particle.

Which is the most unstable elementary particle in an atom?

A radio can tune to any station to 7.3MHz to 12 MHz band. The corresponding wavelength band is

Select the correct statement : (Only force on a particle is due to electric field)

A signal emitted by an antenna from a certain point can﻿ be received at another point of the surface in the form﻿ of﻿

A straight current carrying conductor is kept along the axis of circular loop carrying current . The force exerted by the straight conductor on the loop is …… .

For a radio signal to travel 150 km from the transmitter to a receiving antenna, it takes

Given the mass of iron nucleus as 55.85 u and A = 56, find the nuclear density. (u = 1.67 xx 10 ^(-27) kg, r = 1.2 xx 10 ^(-15)m )

The sun appears to be elliptical during sunset. What is the reason behind it?

A flyover bridge is in the form of a circular arc of radius 39.5m. What is the limiting speed at which a car can cross the bridge without loosing contact with the road, at the highest point ? (Assume that centre of gravity of the car is 0.5 m above the road and g = 10 m/s^2 ).

A rectangular coil of area of cross-section is placed as shown. A magnetic field B is applied along Z-axis. The torque on the coil is

Give two uses of UV rays.

n a Geiger-Marsden experiment, what is the distance of closest approach to the uranium nucleus of a 5.0 MeV alpha-particle before it comes momentarily to rest and reverse its direction?

An electron of charge e and mas m is moving in a circular path of radius r with a unifrom angular speed omega . Then which of the following statementa are correct?

Find theinductance of a unitlength ofa cableconsistingof two thin-walledcoaxialmetalliccylindersif theradiusof theoutside cylinderis eta = 3.6 timesthat of the insideone. Thepermeabitityof a medium betweenthe cylinders is assumedto beequal to unity.

transverse simple harmonic wave is travelling on a string. The equation of the wave:

Explain the determination of unknown resistance usingmeter bridge.

क्षेत्रफल के आधार पर भारत का सबसे बड़ा राज्य कौन सा है?

A system consists of N_(0) nucleus at t = 0. The number of nuclei remaining after half of a half-life (that is, at time t=1/2T_(1/2))

x-y plane separates two media, zge0contains a medium of refractive index 1 and zle0contains a medium of refractive index 2. A ray of light is incident from first medium along a vectorhati+hatj-hatk. Find the unit vector along the refracted ray.

For air or vacuum, K = _____ and fror all other insulating material K = _____.

यदि वस्तु की गति का पथ सरल रेखीय हो,तो ऐसी गति कहलाती है

If force on a particle vecF = (Sin at)hati + (cos at)hatj and displacement vecS = sin(frac{at}{3}hati) + cos(frac{at}{3})hatj are functions of time (t) then value of t at which they are perpendicular for first time is (a is positive constant and t>0)

Which rays are not the portion of electromagnetic﻿ spectrum﻿

In a stationary wave the amplitude of vibrating particle

According to Rutherford, the size of the nucleus is:

Who helped the boy out of his misery?

Find the decay constant and the mean lifetime of Co^(55) radionuclide if its activity is known to decrease4.0% per hour. The decay product is nonradioactive.

To draw the maximum current from a combination of cells, how should be the cells be grounded ?

Three gas molecules have velocities respectively equal

Two plates ( area =s ) charged to + q_(1)and +q_(2)(q_(2) lt q_(1))are brought closer to form a capacitor of capacitance C. The potential difference across the plates is

The time interval observed in a frame at rest is "____________" that observed in a moving frame

If an alpha-particle is projected normally through a uniform magnetic field, then the path of the alpha-particle inside the field will be

A ray of light covers distance .d. in time t, in air and distance 10 d in time t_2, in medium, then critical angle for medium is .....

For a L-C-R series circuit List I - with List-II (Terms have their usual meaning)

A +very charged body attracts a pith ball pendulum towards it Does it mean that the pith ball pendulum is nagatively charged ?

A vessel of depth 2d cm is half filled with a liquid of refractive index mu_(1) and the upper half with a liquid of refractive mu_(2). The apparent depth of the vessel seen perpendicularly is

A signal emitted by an antenna from a certain point can be received at another point of the surface in the form of

For air or vacuum, K = _ and fror all other insulating material K = _.

Which rays are not the portion of electromagnetic spectrum