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InterviewSolution
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.
| 101. |
A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend uponA. shape of the loopB. area of the loopC. number of turns in the loopD. strength of the current |
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Answer» Correct Answer - A The torque acting on it does not depends on shape of the loop. |
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| 102. |
Which of the following resistances must be used to convert galvanometer into voltmeter for maximum sensitiveness ?A. ` 1Omega`B. `10^2Omega`C. `10^5 Omega`D. `10^7 Omega` |
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Answer» Correct Answer - D For maximum sensitivity in case of voltmeter , resistance of galvanometer should be large. |
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| 103. |
A galvanometer has a resistance of `98 Omega` .it is shunted by `2Omega` resistance. The fraction of the total current passing through the galvanometer isA. `2%`B. `2.5%`C. `4%`D. `4.5%` |
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Answer» Correct Answer - A `(I_s)/(I)=(S)/(S+G)=(2)/(100) =-0.02=2%`. |
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| 104. |
The deflection in a M.C.G. is reduced to half , when it is shunted with a `40 Omega` coil. The resistance of the galvanometer isA. `60Omega`B. `40Omega`C. `20Omega`D. `10Omega` |
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Answer» Correct Answer - B From problem (67),we have , `(S)/(S+G)=(theta)/(theta) therefore (12+G)/(12)=(50)/(10)` `therefore G=48Omega`. |
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| 105. |
A positively-charged particle (alpha particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is:A. towards southB. towards eastC. downwardD. upward |
| Answer» Correct Answer - D | |
| 106. |
A uniform magnetic field `barB =B_(0)hatj` exists in a space. A particle of mass m and charge q is projected towards negative x-axis with speed v from the a point `(d,0,0)` The maximum value v for which the particle does not hit `y-z` plane is .A. `(Bqa)/(m)`B. `(Bqa)/(2m)`C. `(Bq)/(am)`D. `(Bq)/(2am)` |
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Answer» Correct Answer - A Here the paticle is projected in a direction perpendicular to the uniform magnetic field hence it will describe a circular path the particle will not hit the yz plane if the radius of the circular path is smaller than a for maximum value of v the radius of circular pth is just equal to a or `V=(Bqa)/(m)` |
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| 107. |
The coil of a suspended coil galvanometer has a very high resistance when a momentary current is passed through the coil. ItA. oscillates with decreases in amplitudeB. oscillates with the sae amplitudeC. gets deflected and comes to rest slowlyD. shows steady deflection |
| Answer» Correct Answer - A | |
| 108. |
A charged particle moving in a uniform magnetic field penetrates a layer of lead and there by loses one-half of its kinetic energy. How does the radius of curvature of its path change?A. The radius increases to `r sqrt(2)`B. The radius reduces to `r//sqrt(2)`C. The radius remains the sameD. The radius becomes `r//2` |
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Answer» Correct Answer - B `E_2 =(E_1)/(2), r_1=r,r_2 =?` `E=(q^2 B^2 r^2)/(2m)` `therefore E prop r^2` `therefore r prop sqrt( E)` `(r_2)/(r_1)=sqrt((E_2)/(E_1))` `therefore r_2=sqrt((E_1)/(2E_1))r_1 =(r_1)/(sqrt(2))= (r ) /(sqrt(2))`. |
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| 109. |
A range of galvanometer is V, when `50Omega` resistance is connected in series. Its range gets doubled when `500Omega` resistance is connected in series. Galvanometer resistance isA. `100Omega`B. `200Omega`C. `300Omega`D. `400Omega` |
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Answer» Correct Answer - D `G=(V_1)/(I_g)-R_1=(V_2)/(I_g)-R_2` `therefore (V)/(I_g)-50=(2V)/(I_g)-500` `therefore V=450I_g` Now, `G=(450I_g)/(I_g)-50=400Omega`. |
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| 110. |
Resistance of galvanometer is `500Omega`. Effective resistance of ammeter with shunt is `25 Omega`. What is the value of shunt ?A. `25 Omega`B. `50 Omega`C. `23.6 Omega`D. `26.3Omega` |
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Answer» Correct Answer - D `I_s((G)/(S+G))I=((48)/(2+48))I=((48)/(50))I` Thus , `96%` of total current will pass through shunt of resistance of `2Omega`. |
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| 111. |
A range of galvanometer is V, when `50Omega` resistance is connected in series. Its range gets doubled when `500Omega` resistance is connected in series. Galvanometer resistance isA. `100 omega`B. `200 omega`C. `300 omega`D. `400 omega` |
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Answer» Correct Answer - D A galvanometer is converted in to a voltmeter when a high resistance is coinnected to it in series It / is maximum current floweing through galvanometer then `V=(R+G)l+(50+G)l…(i)` where V is range of galvanometer when `R =50 omega` is coinnected in series with it and G is galanometer resistance when `500 omega` resistance is connected in series the range on dividing Eqs i by ii we get `(V)/(2V)=(50+G)/(500+G)` or `500+G=100+2G rarr G =400 omega` |
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| 112. |
The current sensitivity of a galvanometer is x div/m A and voltage sensitivity is y div/V . The resistance of galvanometer is G. Then relation between x and y isA. `G=(x)/(y)xx10^3`B. `G=(y)/(x)`C. `G=(x)/(y)`D. `y=Gxx10^3` |
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Answer» Correct Answer - A `S_i=x " div"//mA,S_V=y" div"//V,G=?` `S_V=(S_i)/(G)therefore G=(S_i)/(S_V)` `therefore G=(x xx10^3)/(y)` |
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| 113. |
If K is the restoring torque per unit twist of the fiber and `theta` is the deflection of the coil of M.C.G. then the restoring torque is given byA. `tau=Ktheta`B. `tau= n IAB`C. `tau=K`D. `tau=theta` |
| Answer» Correct Answer - A | |
| 114. |
A galvanometer has a resistance of G ohm and range of V volt. Calculate the resistance to be used in seres with it to extend its range its renge to nV volt.A. nGB. `(G)/(n)`C. `(n-1)G`D. `(G)/(n-1)` |
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Answer» Correct Answer - C A high resistance is connecte in series with coil of the galvanometer to convert it into voltmeter Resistance connected in series is given by `R=(V)/(l_(g))-G` Eq (i) is the value of the resistance required to convert the galvanometer to voltmeter it into voltmeter Resistance conected in series is given by `R=-(V)/(l_(g))-G=(nV)/(V//G)-G` or `R=nG-G=G(n-1)` hence `R=(n-1)G` |
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| 115. |
An electric current passes through a long straight wire. At a distance 5 cm from the wire the magnetic field is `B`. The field at 20 cm from the wire would beA. B/2B. B/4C. B/8D. B |
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Answer» Correct Answer - B `B=(mu_0I)/(2pi a) therefore B prop (1)/(a)` `(B_2)/(B_1)=(a_1)/(a_2) therefore B_2=(B)/(4)` |
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| 116. |
A helium nucleus makes full rotation in a circle of radius 0.8 m in 2.5 seconds. The value of magnetic field B at the centre of the circle will beA. `3.1pi xx10^-26 T`B. `2pi xx10^-26 T`C. `4pi xx10^-25 T`D. `2 pi xx10^-25 T` |
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Answer» Correct Answer - A `B=(mu_0I)/(2a)(I=(q)/(T)=(2e)/(T))` Since for helium , `q=2e` `B=(mu_02e)/(2aT)=(4pi xx 10^-6xx2xx1.6xx10^-19)/(2xx0.8xx2.5)` `B=3.2pi xx10^-26 T`. |
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| 117. |
A solenoid of length 50 cm and a radius of cros section 1 cm has 1000 turns of wire wound over it if the current carried is 5A the magnetic field on its axis near the centre of the solenoid is approximately (Given permeability of free space `mu_(0)=4pi xx10^(-7) T-mA^(-1)`)A. `0.63xx10^(-2)T`B. `1.26 xx10^(-2) T`C. `2.51 xx10^(-2)T`D. `6.3 T` |
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Answer» Correct Answer - B The magnetic field is given by `B=mu_(0)ni` where `mu_(0)=4pixx10^(-7)T mA^(-1)n=(1000)/(50xx10^(-2))I =5A` `therefore` Magnetic field `B=4pi xx10^(-7)xx(1000)/(50xx10^(-3))xx5` `=1.26 xx10^(-2) T` |
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| 118. |
50 turns of a wire of diameter 1mm is wound on a cylinder of radius 5 cm. If the specific resistance of the materical of the wire is `4.5xx10^-6Omegam`, then its resistance isA. `9kOmega`B. `900Omega`C. `250 Omega`D. `90Omega` |
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Answer» Correct Answer - D `n=50,r=0.5mm,a=5cm,rho=4.5xx10^-6Omega m, R=?` `R=(rho^l)/(A)=(rho^l)/(pir^2)=(rho.2pia.n)/(pi r^2)` `therefore R=(rho2an)/(r^2)=(4.5xx10^-6xx2xx5xx10^-2xx50)/(0.25xx10^-6)` `therefore R=9 0 Omega` |
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| 119. |
A long solenoid has 200 turns per cm and carries a current of 2.5A. The magnetic field at its centre isA. `3.14xx10^-2Wb//m^2`B. `6.28xx10^-2Wb//m^2`C. `9.42xx10^-2Wb//m^2`D. `12.56xx10^-2Wb//m^2` |
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Answer» Correct Answer - B `B=mu_0nI` `=4pixx10^(-7)xx200xx10^2xx2.5=6.28xx10^-2T`. |
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| 120. |
Magnetic effects of electric were discovered byA. FaradayB. OerstedC. AmpereD. Joule |
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Answer» Correct Answer - B Magnetic effects of electric current were discovered by Oersted. |
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| 121. |
Magnetic field is measured byA. ammeterB. pyrometerC. flux meterD. thermophile |
| Answer» Correct Answer - C | |
| 122. |
The device used for producing electric current is called a :A. generatorB. galvanometerC. ammeterD. motor |
| Answer» Correct Answer - A | |
| 123. |
Which of the following is the unit of magnetic induction ?A. TB. `Wb//m^2`C. `N//Am`D. all of these |
| Answer» Correct Answer - D | |
| 124. |
Circuit Breaker Device which can be used in place of fuse in domestic electric wiring is called :A. CBDB. DCBkC. MCDD. MCB |
| Answer» Correct Answer - D | |
| 125. |
A long solenoid with 10 turn / cm and a radius of 7.0 cm carries a current of 20.0 mA .A current of 6.0 A exists in a straight conductor loacted along the central axis of the solenoid at what radial distance from the axis will the direction of the magneitic field be at `45^(@)` to the axial directionA. 4.8 cmB. 8.1 cmC. 9.9 cD. 10.6 cm |
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Answer» Correct Answer - A Given for solenoid n=10 truns /cm `I_(1)=20.0 mA=20xx10^(-3) A` `B_(1)` = magnetic field due to solenoid `B_(2)` = magnetic field due to solenoid ltDbrgt `B_(2)` = magnetic field due to wire for wire `l_(2)=6A` Now according to question if resultant should be at `45^(@)` then the two field `B_(1)` and `B_(2)` must be equal to each other so `B_(1)=B_(2) rarr mu_(0)nl_(1)=(m_(0)l_(2))/(2pir)` `rarr` radius `r=(l_(2))/(l_(1)xxn2pi)` `=(6)/(20xx10^(-3)xx102xx3.14)` `=(6xx10^(2))/(20xx2xx3.14)=(60)/(4xx3.14)` =4.77 =4.8 cm (approx) |
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| 126. |
Field inside a toroid isA. directly proportional to its lengthB. directly proportional to currentC. inversely proportional to total number of turnsD. inversely proportional to current |
| Answer» Correct Answer - B | |
| 127. |
SI unit of magnetic pole strength isA. `A//m`B. AmC. `Am^2`D. `A//m^2` |
| Answer» Correct Answer - B | |
| 128. |
If a current is passed in a spring thenA. it is compressedB. it gets expandedC. it performs a vertical SHMD. remains unchanged |
| Answer» Correct Answer - A | |
| 129. |
Magnetic fieldA. can increase the speed of charge particleB. can accelerate a charge particleC. both a and b are correctD. both a and b are incorrect |
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Answer» Correct Answer - B magnetic field can caccelerate a charge particle by chharging the direction of its velocity but it cannot change the speed of charged particle as magentic force always acts perpendiuclar to the velocity of charged particle |
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| 130. |
Two parallel long wires carry currents `i_(1) "and" i_(2)` with `i_(1) gt i_(2)`.When the currents are in the same direction then the magnetic field midway between the wires is `10 mu T.` when the direction of `i_(2)` is reversed ,then it becomes `40 mu T.` then ratio of `i_(1)//i_(2)` isA. 1B. 3C. 2D. 4 |
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Answer» Correct Answer - C When `kl_(2)` and `l_(2)` ar in the same direction `(mu_(0))/(4pi) (2i_(1))/(r )-(mu_(0))/(4pi)(2i_(2))/(r )=10 mu T` when `l_(1)` and `l_(2)` are n the opposite direction `(mu_(0)2i_(1))/(4pir)+(mu_(0))/(4pi)(2i__(2))/(r )=30 muT` on solving `l_(1)=20 A` and `l_(2)` are in the opposite direction `(mu_(0)2l_(1))/(4pi r) +(mu_(0))/(4pi)(l_(1))/(r )=30muT` on solving `l_(1)=20 A` and `l_(2)=10 A` So `(l_(1))/(l_(2))=2` |
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| 131. |
An electric field of 1500 V/m and a magnetic field of 0.40 Wb/`m^(2)` act on a moving electron. The minimum uniform speed along a straight line, the electron could have isA. `16xx10^(15) ms^(-1)`B. `6xx10^(-16) ms^(-1)`C. `3.75 xx10^(3) ms^(-1)`D. `3.75 xx10^(2) ms^(-1)` |
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Answer» Correct Answer - C When electron moves in both electric and magnetic fields then `qE=qvB` so speed of electron `V=(E )/(B)=(1500)/(0.40 )=3750 ms^(-1) rarr V=3.75 xx10^(3) ms^(-1)` |
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| 132. |
A charged particle moves along a circle under the action of passible constant electric and magnetic fields. Which of the following are possible?A. E=0, B=0B. `E=0 , B ne 0`C. `E ne 0, B=0`D. `E ne 0, B ne 0` |
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Answer» Correct Answer - B A charged paritcle moved in a straighit line under the action an electic field whereas it moves in a circular path under the action of a magentic field thhus for the particle moving in a circular path E=0 `B ne 0` |
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| 133. |
Two parallel conductors `A` and `B` of equal lengths carry currents `I` and `10 I`, respectively, in the same direction. ThenA. A and B will repel each other with same forceB. A and B with attract each other with same forceC. A will attract B but will repel AD. A and B will attract each other with different forces |
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Answer» Correct Answer - A Two parllel wires carrying currents in the same direction attract each other because magnetic forces on the two wires act towards each other. |
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| 134. |
A strong magnetic field is applied on a stationary electron, thenA. moves in the direction of the fieldB. moves in an opposite direction of the fieldC. remains stationaryD. starts spinning |
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Answer» Correct Answer - C On static charge. There is no effect of magnetic field. So electron remains stationary. |
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| 135. |
An electron is moving on a circular path of radius `r` with speed `v` in a transverse magnetic field B. e/m for it will beA. `(v)/(Br)`B. `(B)/(rv)`C. BvrD. `(vr)/(B)` |
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Answer» Correct Answer - A As `qv B =(mv^(2))/(r) rArr "Radius", r=(mv)/(qB)` For electron, `r=(mv)/(eB) :. (e)/(B)=(v)/(Br)` |
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| 136. |
Which of the following has largest resistance ?A. ammeterB. milliammeterC. microammeterD. all of these |
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Answer» Correct Answer - C `S=((I_g)/(I-I_g))G=((10^-5)/(1-0.00001))xx100` `10^-3 Omega ` in parallel. |
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| 137. |
A charge q coulomb moves in a circle at n revolution per second and the radius of the circle is r metre. Then magnetic feild at the centre of the circle isA. `(2pi q)/(n r)xx10^-7N//Am`B. `(2piq)/(n r)xx10^-7 N//Am`C. `(2pi n q)/(r)xx10^-7N//Am`D. `(2pi q)/(n r)N//Am` |
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Answer» Correct Answer - C `B=(mu_0I)/(2r)=(4pixx10^-7xxnq)/(2r)` `=(2pinq)/(r)xx10^(-7)N//Am" "[because I=(nq)/(t)]` |
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| 138. |
A `2MeV` proton is moving perpendicular to a uniform magnetic field `2.5` tesla. The force on the proton isA. `8xx10^-10N`B. `4xx10^-10N`C. `6xx10^-10N`D. `8xx10^-12N` |
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Answer» Correct Answer - D `E_k=(1)/(2)mv^2{v=2xx10^7 m//s)`. `F=qv Bsin 90 =8xx10^-12N`. |
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| 139. |
An ammeter has resistance `R_(0)` and range l what resistance should be connected in parallel with it to increase its range by nl ?A. `R_0//n`B. `R_0//(n-1)`C. `R_0(n+1)`D. `R_0(n+1)` |
| Answer» Correct Answer - B | |
| 140. |
To measure the current in an electric deviceA. put an ammeter in parallel with itB. put a voltmeter in parallel with itC. put an ammeter in series with itD. put a voltmeter in series with it |
| Answer» Correct Answer - C | |
| 141. |
When an ammeter is connected in parallel the resistance of the circuit isA. increasedB. decreasedC. is unchangedD. none of these |
| Answer» Correct Answer - B | |
| 142. |
The parallel combination of galvanometer and shunt is calledA. voltmeterB. ohmmeterC. ammeterD. speedometer |
| Answer» Correct Answer - C | |
| 143. |
An ammeter is aA. low resistance galvanometer and is always connected in parallel with a circuitB. low resistance galvanometer and it is always connected in series with the circuitC. hight resistance galvanometer and is always connected in series with the circuitD. high resistance galvanometer and is always connected in parallel with the circuit |
| Answer» Correct Answer - B | |
| 144. |
The function of shunt resistance in ammeter isA. it lowers resistance of galvanometerB. it protects galvanometerC. it decides range of ammeterD. all of these |
| Answer» Correct Answer - D | |
| 145. |
Of the following graphs , the one which shows the relationship between the resistance R of multirange moving coil ammeter and its range I isA. B. C. D. |
| Answer» Correct Answer - C | |
| 146. |
The requirements of ideal ammeter areA. it resistance should be nearly zeroB. it should be direct reading typeC. it should be sensitive and accurateD. all of these |
| Answer» Correct Answer - D | |
| 147. |
The requirements of ideal ammeter areA. its resistance should be largeB. it should be direct reading typeC. it should be sensitive and accurateD. all of these |
| Answer» Correct Answer - D | |
| 148. |
The resistance of an ideal ammeter isA. lowB. zeroC. highD. infinite |
| Answer» Correct Answer - B | |
| 149. |
An ammeter should have very low resistance, so that it mayA. not burn outB. have better stabilityC. show large deflectionD. not change the value of the current |
| Answer» Correct Answer - D | |
| 150. |
An ammeter has resistance `R_(0)` and range l what resistance should be connected in parallel with it to increase its range by nl ?A. `n G `B. `G//n`C. `(n-1)G`D. `G//(n-1)` |
| Answer» Correct Answer - D | |