45406 + Interview Questions in Physics in Class 12 Page 146 InterviewSolution

7251.	Series LCR circuit is connected to an AC source of angular frequency omega. Current flowing in the circuit is found to lead the voltage by pi/4. Magnitude of capacitance is
Answer» `(1)/(OMEGA^(2) (L + R))` `(1)/(omega (L + R))` `(1)/(omega^(2) L + omega R)` `(1)/(omega L + omega^(2) R)` SOLUTION :(c ): Phase difference of `pi//4 ` or `45^(@)` between current and VOLTAGE means NET reactance of circuit is equal to resistance of circuit . Further it is given that current leads the voltage hence reactance due to capacitance is more than due to inductor . Hence we can write the following equation : `(1)/(omegaC ) - omegaL = R ` `implies (1)/(omegaC )= R + omegaL` `implies (1)/(omegaC)=R+omegaL` `implies C = (1)/(omega^(2)L+omegaR)` Hence optioin C is correct .

Discussion

7252.	There are two concentric spherical shells with inner shell having positive charge q and outer shell having a charge -q. Now outer shell is supplied a charge -2g and inner shell is earthed, Calculate the ratio of initial and final capacities of the system. (If a = 3R, b= 5 R)
Answer» `3//5` 3 1 `5//3` ANSWER :A

Discussion

7253.	Angular momentum of the earth revolving around the sun is proportional to r^(n), where r is the distance between the earth and the sun. Value of n is :
Answer» 2 1 `1//2` `3//2` Solution :Here `(mv^(2))/(R)=(GMM)/(r^(2))vsqrt((GM)/(r))` `L=mvr=msqrt((GM)/(r)).r=msqrt(GMR)Lpropr^(1//2)`

Discussion

7254.	State the two rules that serve as general rules foranalysis of electrical circuits. Use these rules to write the three equations that may be used to obtain the values of the three unknown currents in the branches (shown) of the circuit
Answer» Solution : As per Kirchhoff.s FIRST law the distribution of current in various branches of NETWORK are as shown in Fig.Applying Kirchhoff.s second law to mesh ABDA, we have ` - I_2. R_1 - (I_3 + I_2) R_3 - I_1 . r+ E_1 = 0` ` rArr I_1 .r + I_2 (R_1 + R_3) + I_3 . R_3 = E_1`....(i) For mesh ACDA ,we have ` - (I_1 - I_2) R_2 + (I_3 + I_2 - I_1) R_4 - I_1.r + E_1 = 0` ` rArr I_1 (R_2 + R_4 + r) + I_2 (R_2 - R_4) - I_3.R_4 = E_1` and for mesh `E_2 BDCE_2` , we have `- I_3.r-(I_3 + I_2)R_3 - (I_3 + I_2 - I_1)R_4 + E_2 = 0` ` rArr- I_1.R_4 + I_2. (R_3 + R_4) + I_3.(r + R_3 + r_4) = E_2` On simplifying these three equations we can find the value of currents FLOWING in various branchesof the circuit

Discussion

7255.	A negligibly small current is passed through a wire of length 20 m and uniform cross-section 6.0 xx 10^(7) m^(2), and its resistance is measured to be 10.0 Omega . What is the resistivity of the material at the temperature of the experiment ?
Answer» Solution :Resistance of a CONDUCTING WIRE is R = `(rho l)/(A)` `rho = (RA)/(l)` `= (5 xx 6 xx 10^(7))/(15)` `rho = 2 xx 10^(-7) Omega` m

Discussion

7256.	Draw a labelled ray diagram of an astronomical telescope in the near point adjustment position. A giant refracting telescope at an observatory has an objective lens of focal length 15 m and an eyepiece of focal length 1.0 cm. If this telescope is used to view the Moon, find the diameter of the image of the Moon formed by the objective lens. The diameter of the Moon is 3.48 xx 10^(6) m, and the radius of lunar orbit is 3.48 xx 10^(8) m
Answer» Solution :(B) `U=-25cm` `V=-50cm` `(1)/(f)=(1)/(v)-(1)/(u)=(1)/(-50)-(-(1)/(25))=(1)/(50)` `rArr""f=+50cm` `"POWER, P"=(100)/(f(cm))=(100)/(50)=+2D`

Discussion

7257.	Define toatal internal reflection.State its essential conditions.
Answer» Solution :Total Internal Reflaction : When LIGHT passes from an optically DENSER medium to a rarer medium at the interface, under certain conditions the incident light can be made to be reflected BACK into the same medium without any loss of intensity.This pheomenon is called Total Internal Reflaction. Essential Conditions : (i) Light should travel from a denser medium to a rarer medium. (II) Angle of incidence in densor medium should be greater than the critical angle for the PAIR of media in contact.

Discussion

7258.	A motor with an efficiency of 90% drives a pump, whose efficiency is 60%. Then the efficiency of the entire installation is :
Answer» 0.75 0.54 0.45 0.3 Answer :B

Discussion

7259.	In LC oscillator circuit, at t = 0, ……
Answer» TIME rate of flow of electric charge is maximum. time rate of flow of electric charge is zero. time rate of flow charge of electric CURRENT is zero. time rate of flow charge of electric current is minimum. Solution :We have : `i=-q_0 omegasin(omegat)` `rArr` At time `t=0 , i=0 rArr (dq)/(DT) =0`

Discussion

7260.	(A): The semiconductors do not obey ohm's law. (R): In semi conductors, the resistance depends on magnitude and direction of applied electric field.
Answer» Both 'A' and 'R' are TRUE and 'R' is the CORRECT explanation of 'A' Both 'A' and 'R' are true and 'R' is not the correct explanation of 'A' 'A' is true and 'R' is false 'A' is false and 'R' is false ANSWER :A

Discussion

7261.	The average emf induced in a coil in which the current changes from 2 A to 4 A in 0.05 s is 8 V. Self-inductance of the coil is
Answer» 0.1 H 0.2H 0.4H 0.8H Solution :`\|epsi\|=L ""(d I)/(dt)=L ((I_(2)-I_(1))/(t)) THEREFORE L=(\|epsi\|t)/((I_(2)-I_(1)))= (8 XX 0.05)/((4-2))=0.2H`

Discussion

7262.	8^(4/3)निम्नलिखित में किसके बराबर है?
Answer» 16 8 4 2 Answer :A

Discussion

7263.	How much height of water in cm would be filled in a container of height 14 cm,so that it appears half filled to the observer when viewed from the top of the container (mu_(omega)=4/3)
Answer» ANSWER :6

Discussion

7264.	In a biprism experiment, the distance between the slit and the focal plane of the eyepiece is 1.2 mand the wavelenght of light used is 5000Å. When a convex lenz is interposed (between the biprism and eyepiece) the images of the slits in the two positios are 5mm and 1.8 mm part. the distance betwene the centre of the pattern and twelfth dark band is
Answer» `1.3XX10^(-3) m` `2.2xx10^(-3) m` `3.3xx10^(-3) m` `2.3xx10^(-3) m` Solution :`x_(12d)=11.5beta=11.5(Dlamda)/(d)=(11.5xx1.2xx5xx10^(-7))/(3xx10^(-3))` `=2.3xx10^(-3)m`

Discussion

7265.	What is theradius of the illumination when seen above from inside a swimming pool from a depth of 10 m on a sunny day? What is the total angle of view? [ Give refractive index of water is 4/3]
Answer» Solution :Give: n = 4/3,d = 10 m Radiua of illumination, R = `(d)/(sqrt(n^(2) - 1))` `R = (10)/(sqrt((4//3)^(2)-1))=(10xx3)/(sqrt(16-9)),R=(30)/(sqrt(7)) = 11.32` To find the ANGLE of the VIEW of the cone, `i_(r) = SIN^(-1) ((1)/(n))` `i_(E)=sin^(-1)((1)/(4//3))=sin^(-1)((3)/(4))=48.6^(@)` The total angle of view is, `2i_(c ) = 2 xx 48.6^(@) = 97.2^(@)`

Discussion

7266.	Two containers of equal volume contain the same gas at pressure P_(1) and P_(2) and absolute temperature T_(1) and T_(2), respectively. On joining the vessels, the gas reaches a common pressure P and common temperature T. The ratio P//T is equal to
Answer» `(p_(1)T_(2)+p_(2)T_(1))/(T_(1)xxT_(2))` `(p_(1)T_(2)+p_(2)T_(1))/(T_(1)+T_(2))` `(1)/(2)[(p_(1)T_(2)+p_(2)T_(1))/(T_(1)T_(2))]` `(p_(1)T_(2)-p_(2)T_(1))/(T_(1)xxT_(2))]` ANSWER :C

Discussion

7267.	Radius of first Bohr orbit is r . What is the radius of 2^(nd)Bohr orbit?
Answer» `8r` `2r` `4R` `2 SQRT(2r)` ANSWER :C

Discussion

7268.	A hydrogen atom is in ground state. In order to get six lines in its emission spectrum, wavelength of incident radiation should be
Answer» `800Å` `825Å` `975Å` `1025Å` ANSWER :C

Discussion

7269.	Define 1 eV.
Answer» SOLUTION :1 EV is the energygained by an electronwhen it is ACCELERATED by a POTENTIAL difference of `\|V.\| eV=1.609 xx 10^(-19)J`.

Discussion

7270.	A neutral atom which is stationary at the origin in gravity -free space emits an alpha- particle (A) in the z-direction. The product atom is P. A uniform magnetic field exists in the x-direction. Disregard the electrostatic forces between A and P.
Answer» `A` and `P` will move along CIRCULAR parths of equal RADII. `A` has greater time period of ROTATION than `P` `A` has greater KINETIC energy than `P` `A` and `P` will meet again somewhere in the `yz` plane. Answer :A::C::D

Discussion

7271.	Two moving coil metres M_(1) and M_(2) have the following particular R_(1) =10Omega, N_(1) =30, A_(1) = 3.6 xx 10^(-3) m^(2), B_(1) =0.25 T, R_(2) = 14Omega , N_(2) =42, A_(2) = 1.8 xx 10^(-3) m^(2), B_(2) =0.50 T The spring constants are identical for the two metres. What is the ratio of current sensitivity and voltage sensitivity of M_(2)" to" M_(1)?
Answer» Solution :(a) Current SENSITIVITY, `(phi)/(I) = (NBA)/(K)` Ratio of current Sensitivity `= ((N_1 B_1 A_1)/(K))//((N_2 B_2 A_2)/(K))` `= (30 xx 0.25 xx 3.6 xx 10^(-3))/(42 xx 0.50 xx 1.8 xx 10^(-3))= 5//7` (b) VOLTAGE sensitivity, `(phi)/(V)= (NBA)/(k R)` Ratio of voltage sensitivity = `((N_1 B_1 A_1)/(kR_1))//((N_2 B_2 A_2)/(kR_2))` `= (30xx 0.25 xx 3.6 xx 10^(-3) x 14)/(42 xx 0.50 xx 1.8 xx 10^(-3) xx 10)=1`

Discussion

7272.	One end of a steel wire is attached to a fixed support and the other end is attached to a string, which is going over a pulley and is connected to a block, whch is hanging vertically. It is observed that the wire vibrates in its fundamental mode with frequency of 200 Hz. When the block is submerged in water, the same wire vibrates in its 1 harmonic with frequency of 100 Hz. Density of steel wire is 8000 kg//m^(3) and length of wire is 1 m.
Answer» ANSWER :a-q, b-p, c-s, d-r

Discussion

7273.	A ball is projected horizontally with a velocity of 5ms^(-1)from the top of a tower of height 10 m. When it reaches the ground (g=10 ms^(-2))
Answer» ANSWER :`15 MS^(-1)`

Discussion

7274.	Find the frequency of light which ejects electrons from a metal surface, fully stopped by a retarding potential of 3V. The photoelectric effect begins in this metal at frequency 6xx10^(14)s^(-1)
Answer» `10^(5)` `10^(16)` `1.324xx10^(15)` none of these. Solution :`hv=E_(k)+w "" :. E_(k)=hv-w` If `V_(s)` is retarding POTENTIAL then `E_(k)=eV_(s) and w=hv_(0)` `:.eV_(s)=hv-hv_(0)` or `v=(eV_(s))/(H)+v_(0)` Given `V_(s)=3V, v_(0)=6xx10^(-14)s^(-1)` `:.` REQUIRED frequencyv is `v=(16xx10^(-19)xx3)/(662xx10^(-34))+6xx10^(14)` `v=1*324xx10^(15)` per sec.

Discussion

7275.	Given 'n' resistors each of resistance R, how will you combine them to get the (i) maximum (ii) minimum effective resistance/What is the ratio of the maximum to minimum resistance ?
Answer» SOLUTION :(i) in SERIES (II) all in PARALLEL ,`n^2 `.

Discussion

7276.	The following terms find importance in magnetism . Explain them a. Magnetic permeability (mu) b. Magnetic intensity (H) c. Intensity of magnetisation (I) d. Magnetic susceptibility (X_m)
Answer» Solution :a. Magnetic permeability is the ratio of magnetic INDUCTION to magnestising field STRENGTH Permeability , `mu=B/H` b. It is the field produced by the Amperian current. If n is the number of turns of a SOLENOID and I - the current through it, then H = nI. It is the magnetic field magnetises the medium and is called magnetic intensity. c. Intensity of magnetisation is DEFINED as the magnetic moment per unit volume. `I=M/V,M` - magnetic moment , V - volume d. The ratio of intensity of magnetisation to the MAGNETISING field strength is defined as magnetic susceptibility (X) `X=I/H`

Discussion

7277.	If the sum of two unit vector is also unit vector, then magnitude of their difference is
Answer» `SQRT 2` `sqrt 3` `sqrt 4` `sqrt 7` Answer :B

Discussion

7278.	A body in a room cools from 85^(@)C to 80^(@)C in 9 minutes. The time taken to cool from 80^(@)C to 75^(@)C is :
Answer» 9 minutes LESS than 9 minutes more than 9 minutes ether less or more than five minutes. Solution :Since TEMPERATURE difference between body and surrounding keeps on decreasing. `:.` By Newton.s law of cooling the RATE of loss of heat decreases `rArr` time increases. Hence correct CHOICE is (C ).

Discussion

7279.	Calculate the relaxation time of electron in previous problem. Given mass of electronis 9.1 xx10^(-31) kg.
Answer» SOLUTION :`1.37xx10^(-17)s`

Discussion

7280.	Four charges of 1 mC, 2mC, 3mC and- 6 mC are placed one at each corner of the square of side 1m. The square lies in the x-y plane withits centre at the origin.
Answer» The electric POTENTIAL is ZERO at the origin. The electric potential is zero EVERYWHERE along the x-axis only on the SIDES of the square which are parallel to y axis. The electric potential is zero everywhere along the z-axis for any orientation of the square in the x-y PLANE. The electric potential is not zero along z-axis except at the origin. Answer :A::C::D

Discussion

7281.	Power in a.c. circute is given by emf and current related by ?
Answer» SOLUTION :`P_av=[E_v XX I_v]`

Discussion

7282.	The selling rate of a radioactive isotope is decided by its activity. What will be the second-hand rate of a one month ""^(32)P(t_(1//2) = 14.3 days) source if it was originally purchased for 800 rupees?
Answer» ANSWER :187 RUPEES

Discussion

7283.	A siphon of uniform diameter is used to drain water from a tank as illustrated in Fig. Assuming steady flow without friction, consider a small hole in the hose at location D as indicated . When the siphon is used , will water leak out of the hose , or will air leak into the hose and thus causing the siphon to stop ?
Answer» SOLUTION :Air will LEAK into the HOSE and siphon STOPS .

Discussion

7284.	Complete the following nuclear reactions : (a) " "_(5)^(10)B + " "_(0)^(1)n to " "_(2)^(4)He +........ (b) " "_(42)^(94)M"o"+ " "_(1)^(2)H to " "_(43)^(95)Te +.........
Answer» SOLUTION :Considering conservation of atomic number as WELL as MASS number, the completed nuclear reactions may be expressed as : (a) `" "_(5)^(10)B +" "_(0)^(1)nto " "_(2)^(4)He + " "_(3)^(7)Li` (b) `" "_(42)^(94)M"o"+ " "_(1)^(2)H to " "_(43)^(95)Te + " "_(0)^(1)n`

Discussion

7285.	The original Ferris wheel was built in 1893 by George Washington Gale Ferris, Jr., a civil engineering. The wheel, an amazing engineering construction at the time, carried 36 wooden cars, each holding as many as 60 passengers, around a circle of radius R = 38 m. The mass of each car was about 1.1xx10^(4)kg. The mass of the wheel's structure was about 6.0xx10^(5)kg, which was mostly in the circular grid from which the cars were suspended. The wheel made a complete rotation at an angular speed omega_(F) in about 2 min. (a) Estimate the magnitude L of the angular momentum of the wheel and its passengers while the wheel rotated at omega_(F). (b) If the fully loaded wheel is rotated from rest to omega_(F) in a time period Deltat_(1)=5.0s, what is the magnitude t_(avg) of the avergae net external torque acting on it?
Answer» Solution :(a) We can treat the wheel, cars, and passengers as a rigid object rotating about a fixed axis, at the wheel.s axle. Then Eq. `(L=Iomega)` gives the magnitude of the angular momentum of that object. We NEED to find `omega_(F)` and the rotational inertia I of this object. Calculations: Rotational inertia: To find I, let us start with the loaded cars. Because we can treat them as particles, at distance R from the axis of rotation, we know from Eq. That their rotational inertia is `I_(pc)=M_(pc)R^(2),"where "M_(pc)` is their total mass. Let us assume that the 36 cars are each filled with 60 passengers, each of mass 70 kg. Then their total mass is `M_(pc)=36[1.1xx10^(4)kg+60(70kg)]=5.47xx10^(5)kg` and their rotational inertia is `I_(pc)=M_(pc)R^(2)=(5.47xx10^(5)kg)(38m)^(2)=7.90xx10^(8)kgm^(2)` Next, we consider the structure of the wheel. Let us assume that the rotational inertia of the structure is due mainly to the circular grid suspending the cars. Further, let us assume that the grid forms a hoop of radius R, with a mass `M_("hoop")" of "3.0xx10^(5)kg` From, the rotational inertia of the hoop is `I_("hoop")=M_("hoop")R^(2)=(3.0xx10^(5)kg)(38m^(2))` = `4.33xx10^(8)kgm^(2)` The combined rotational inertia I of the cars, passengers, and hoop is then `I=I_(pc)+I_("hoop")=7.90xx10^(8)kgm^(2)+4.33xx10^(8)kgm^(2)` = `1.22xx10^(9)kgm^(2)` Angular speed : TO find the rotational speed `omega_(F)`, we use `omega_(avg)=Deltatheta//DELTAT`. Here the wheel goes through an angular DISPLACEMENT of `Deltatheta=2pi` rad in a time period `Deltat=2min`. Thus, we have `omega_(F)=(2pirad)/((2min)(60s//min))=0.0524rad//s` Angular momentum: Now we can find the magnitude L of the angular momentum with Eq. `L=Iomega_(F)=(1.22xx10^(9)kgm^(2))(0.0524rad//s)` = `6.39xx10^(7)kgm^(2)//s~~6.4xx10^(7)kgm^(2)//s` (b) Conceptualize/Classify: The average NET external torque is related to the change `DeltaL` in the angular momentum of the loaded wheel by Eq. `(vectau_("net")=dvecL//dt)`. Compute: Because the wheel rotates about a fixed axis to reach angular speed `omega_(F)` in time period `Deltat_(1)`, we can reqriye Eq. `tau_(avg)=DeltaL//Deltat_(1)` The change `DeltaL` is from zero to the answer for part (a). Thus, we have `tau_(avg)=(DeltaL)/(Deltat_(1))=(6.39xx10^(7)kgm^(2)//s-0)/(5.0s)` `~~1.3xx10^(7)Nm`

Discussion

7286.	The velocity v of a particle at timet is given by v = at + (b)/(t + c) , where a, b and c are constants. The dimensions of a, b and c are respectively
Answer» `LT^(-2)`, L and T `L^(2)`, T and `LT^(2)` `LT^(2)`, LT and L L , `LT and T^(2)` ANSWER :A

Discussion

7287.	The flux linked with a coil at any instant 't' is given by phi=10t^2-50t+250. The induced emf at t=3s is ____
Answer» 10 V 190 V `-190V` `-10V` Solution :Induced EMF `EPSILON=-(dphi)/(dt)=-d/(dt)[10t^2-50t+250]` =-[20t-50] Taking t=3 `THEREFORE epsilon=-[20xx3-50]` =-[60-50] `therefore epsilon` =-10 V

Discussion

7288.	Statement-1: Twoparticles of mass 1 kg and 3 kg move towards each other under their mutual force of attraction. No other force acts on them. When the relative velocity of approach of the two particles is 2 m//s, their centre of mass has a velocity of 0.5 m//s. When the relative velocity of approach becomes 3 m//s the velocity of the centre of mass is 0.75 m//s. Statement-2: The total kinetic energy as seen from ground is 1/2muv_(rel)^(2)+1/2mv_(c)^(2) and in absence of external force, total energyremains conserved.
Answer» `0.75 MS ^(-1)` `0.5 ms ^(-1)` `10 ms ^(-1)` `1.25 ms ^(-1)` ANSWER :B

Discussion

7289.	A very long straight wire carries a current I. At the instant when a charge +Q at point P has velocity vecv, as shown, the force on the charge is
Answer» ALONG OY opposite to OY along OX opposite to OX Answer :A

Discussion

7290.	(a) Use the Bio-Savart law to determine the magnetic field due to conduction current outside the plates (refer to Fig) at points 6.5cm,12cm and 15cm from the wire. Do the answer match with those in Ex. ? Explain. (b) If the conduction wire has a radius of 1.0mm, what is the maximum value of magnetic field due to the conduction current? [When you compare the answer to Ex.(b) and 6(b), you will appreciate why it is not easy to notice magnetic field due to the displacement current]. (c) Suppose the thin wire in Fig. is replaced by rods each of radius 12cm (i.e. we now have two long cylinder rods separated by a small gap). Will magnetic field configurations for r gt R be identical for the regions between the plates and outside the plates?
Answer» Solution :(a) USING Biot-Savart law, mangetic field induction at a point outside a straight current carrying wire is given by `B=(mu_0I_D)/(2pir)` Now, since `I=I_D`, this formula is the same as in for `r gt R`. THEREFORE , for `r=12cm` and `15 cm`, answers are the same as INFOR `r=6.5 cm (r lt R)`, the two formulae differ. Here `B=4.6xx10^-7T`, greater than B is (b) B is maximum at the surface of the wire, `B=(mu_0I)/(2pir)=(4pixx10^-7)/(2pixx10^-3)=3.0xx10^-6T` [Here, `r=1.0mm=10^-3m]` This is much greater than the maximum value of B INDUE to this reason, it is not easy to notice magnetic field due to displacement current. (c) YES, since`I=I_D`, magnetic field Configuration are identical for `r gt R`.

Discussion

7291.	A fork A has frequency 2% more than the standard fork and B has a frequency 3% less than the frequency of same standard fork. The forks A and B when sounded together produced 6 beats s^(-1) . The frequency of fork A is
Answer» 116.4 Hz 120 Hz 122.4 Hz 238.8 Hz Solution :LET `UPSILON` be frequency of standard fork. The frequency of A, `upsilon_A=upsilon+2/100 upsilon` the frequency of B, `upsilon_B=upsilon-3/100upsilon` According to QUESTION , `upsilon_A-upsilon_B=6` `therefore (upsilon+ 2/100upsilon)-(upsilon-3/100upsilon)=6` `5/100 upsilon =6` or `upsilon=600/5`=120 Hz The frequency of A `upsilon_A=(upsilon + 2/100upsilon)=120+ 2/100 XX 120` = 122.4 Hz

Discussion

7292.	The alloys used for muscle wires in Robots are
Answer» SHAPE MEMORY alloys Gold COPPER alloys Gold silver alloys Two DIMENSIONAL alloys Answer :a

Discussion

7293.	A point charge q is placed with in the cavity of an electrically neutral conducting shell whose outer surface has spherical shape. Then,
Answer» The potential V at point P lying outside the shell at a distance r from the centre O of the OUTER surface depends UPON the value of x. potential at P does not depend upon the value of x. a total charge q will be induced on the outer surface the shell which will be DISTRIBUTED uniformly on the outer surface. a total charge -q will be induced on the inner surface of the shell which will be distributed nonuniformly on the inner surface. SOLUTION :b.,c.,d. `V_(p)=(kq)/(r)` (INDEPENDENT of `x`)

Discussion

7294.	In the circuit shown in fig., the base current I_(B) is 10muA and the collector current is 5.2mA. (a) Can this transistor circuit be used as an amplifier? (b) What happen if the resistance R_(C) is 500Omega and I_(B), I_(C) and R_(B) remain same as above?
Answer» ANSWER :NA

Discussion

7295.	A galvanometer has a resistance of 25Omega and a maximum of 0.01A current can be passed through it. In order to change it, into an ammeter of range 10A, the shunt resistance required is
Answer» 5/999 `OMEGA` 10/999 `Omega` 15/999 `Omega` 25/999 `Omega` ANSWER :D

Discussion

7296.	A wheel with 10 metallic spokes each 0.5m long is rotated with a speed of 120 "rev"//"min" in a plane normal to the earth.s magnetic field at the place. If the magnitude of the field is 0.4 G, the induced e.m.f. between the axle and the rim of the wheel equal to
Answer» `1.256 XX 10^(-3)` V `6.28 xx 10^(-4)` V `1.256 xx 10^(-4)` V `6.28 xx 10^(-5)` V Answer :D

Discussion

7297.	A region has a uniform magnetic field in it. A proton enters into the region with velocity making an angle of 45° with the direction of the magnetic field. In this region the proton will move on a path having the shape of a
Answer» STRAIGHT line. circle spiral. HELIX. Solution :(d) helix.

Discussion

7298.	What is average power of AC circuit containing inductance only ?
Answer» SOLUTION :`P_av =E_0I_0/2 COS PHI` Now, `phi = pi/2, cos phi = O` `THEREFORE `P_av = 0`

Discussion

7299.	A particle with charge 2.0 C movess through a uniform magnetic field. At one instant the velocity of the particle is (2.0hati+4.0hatj+6.0hatk) m//s and the magnetic force on the particle is (4.0hati-20hatj+12hatk) N. The x and y components of the magnetic fields are equal. What is vecB ?
Answer» ANSWER :`VECB=(-3.0hati-3.0hatj-4.0hatk)T`

Discussion

7300.	Tabulate End rule polarity with direction of current in circular loop using module.
Answer» SOLUTION :

Discussion

Explore topic-wise InterviewSolutions in .

Series LCR circuit is connected to an AC source of angular frequency omega. Current flowing in the circuit is found to lead the voltage by pi/4. Magnitude of capacitance is

There are two concentric spherical shells with inner shell having positive charge q and outer shell having a charge -q. Now outer shell is supplied a charge -2g and inner shell is earthed, Calculate the ratio of initial and final capacities of the system. (If a = 3R, b= 5 R)

Angular momentum of the earth revolving around the sun is proportional to r^(n), where r is the distance between the earth and the sun. Value of n is :

State the two rules that serve as general rules foranalysis of electrical circuits. Use these rules to write the three equations that may be used to obtain the values of the three unknown currents in the branches (shown) of the circuit

A negligibly small current is passed through a wire of length 20 m and uniform cross-section 6.0 xx 10^(7) m^(2), and its resistance is measured to be 10.0 Omega . What is the resistivity of the material at the temperature of the experiment ?

Define toatal internal reflection.State its essential conditions.

A motor with an efficiency of 90% drives a pump, whose efficiency is 60%. Then the efficiency of the entire installation is :

In LC oscillator circuit, at t = 0, ……

(A): The semiconductors do not obey ohm's law. (R): In semi conductors, the resistance depends on magnitude and direction of applied electric field.

The average emf induced in a coil in which the current changes from 2 A to 4 A in 0.05 s is 8 V. Self-inductance of the coil is

8^(4/3)निम्नलिखित में किसके बराबर है?

How much height of water in cm would be filled in a container of height 14 cm,so that it appears half filled to the observer when viewed from the top of the container (mu_(omega)=4/3)

What is theradius of the illumination when seen above from inside a swimming pool from a depth of 10 m on a sunny day? What is the total angle of view? [ Give refractive index of water is 4/3]

Two containers of equal volume contain the same gas at pressure P_(1) and P_(2) and absolute temperature T_(1) and T_(2), respectively. On joining the vessels, the gas reaches a common pressure P and common temperature T. The ratio P//T is equal to

Radius of first Bohr orbit is r . What is the radius of 2^(nd)Bohr orbit?

A hydrogen atom is in ground state. In order to get six lines in its emission spectrum, wavelength of incident radiation should be

Define 1 eV.

A neutral atom which is stationary at the origin in gravity -free space emits an alpha- particle (A) in the z-direction. The product atom is P. A uniform magnetic field exists in the x-direction. Disregard the electrostatic forces between A and P.

A ball is projected horizontally with a velocity of 5ms^(-1)from the top of a tower of height 10 m. When it reaches the ground (g=10 ms^(-2))

Find the frequency of light which ejects electrons from a metal surface, fully stopped by a retarding potential of 3V. The photoelectric effect begins in this metal at frequency 6xx10^(14)s^(-1)

Given 'n' resistors each of resistance R, how will you combine them to get the (i) maximum (ii) minimum effective resistance/What is the ratio of the maximum to minimum resistance ?

The following terms find importance in magnetism . Explain them a. Magnetic permeability (mu) b. Magnetic intensity (H) c. Intensity of magnetisation (I) d. Magnetic susceptibility (X_m)

If the sum of two unit vector is also unit vector, then magnitude of their difference is

A body in a room cools from 85^(@)C to 80^(@)C in 9 minutes. The time taken to cool from 80^(@)C to 75^(@)C is :

Calculate the relaxation time of electron in previous problem. Given mass of electronis 9.1 xx10^(-31) kg.

Four charges of 1 mC, 2mC, 3mC and- 6 mC are placed one at each corner of the square of side 1m. The square lies in the x-y plane withits centre at the origin.

Power in a.c. circute is given by emf and current related by ?

The selling rate of a radioactive isotope is decided by its activity. What will be the second-hand rate of a one month ""^(32)P(t_(1//2) = 14.3 days) source if it was originally purchased for 800 rupees?

Complete the following nuclear reactions : (a) " "_(5)^(10)B + " "_(0)^(1)n to " "_(2)^(4)He +........ (b) " "_(42)^(94)M"o"+ " "_(1)^(2)H to " "_(43)^(95)Te +.........

The velocity v of a particle at timet is given by v = at + (b)/(t + c) , where a, b and c are constants. The dimensions of a, b and c are respectively

The flux linked with a coil at any instant 't' is given by phi=10t^2-50t+250. The induced emf at t=3s is ____

A very long straight wire carries a current I. At the instant when a charge +Q at point P has velocity vecv, as shown, the force on the charge is

A fork A has frequency 2% more than the standard fork and B has a frequency 3% less than the frequency of same standard fork. The forks A and B when sounded together produced 6 beats s^(-1) . The frequency of fork A is

The alloys used for muscle wires in Robots are

A point charge q is placed with in the cavity of an electrically neutral conducting shell whose outer surface has spherical shape. Then,

In the circuit shown in fig., the base current I_(B) is 10muA and the collector current is 5.2mA. (a) Can this transistor circuit be used as an amplifier? (b) What happen if the resistance R_(C) is 500Omega and I_(B), I_(C) and R_(B) remain same as above?

A galvanometer has a resistance of 25Omega and a maximum of 0.01A current can be passed through it. In order to change it, into an ammeter of range 10A, the shunt resistance required is

A wheel with 10 metallic spokes each 0.5m long is rotated with a speed of 120 "rev"//"min" in a plane normal to the earth.s magnetic field at the place. If the magnitude of the field is 0.4 G, the induced e.m.f. between the axle and the rim of the wheel equal to

A region has a uniform magnetic field in it. A proton enters into the region with velocity making an angle of 45° with the direction of the magnetic field. In this region the proton will move on a path having the shape of a

What is average power of AC circuit containing inductance only ?

A particle with charge 2.0 C movess through a uniform magnetic field. At one instant the velocity of the particle is (2.0hati+4.0hatj+6.0hatk) m//s and the magnetic force on the particle is (4.0hati-20hatj+12hatk) N. The x and y components of the magnetic fields are equal. What is vecB ?

Tabulate End rule polarity with direction of current in circular loop using module.