2nd Physics Short Ans + MCQ

8/7/2019 2nd Physics Short Ans + MCQ

1/23

SOLUTION OF BOOK QUESTIONS 2nd YEAR PHYSICS

CHAPTER # 12Q#1

The potential is constant throughout a given region of space .isthe electric field is zero or non zero in this region?

Ans#1:Electric field E and potential difference are related by equation,

E =- v/ rWhen the potential is taken as constant which means v= constant then the

potential difference becomes zero v=0 so,E =0/r E = 0

This relation tells that electric field is zero in a region of where the

potential is constantQ#2:

Suppose that you follow an electric field line due to a positivepoint charge .do electric field and the potential increases or decreases?Ans#2:

Relation for the electric field and and electric potential are

E= 1/4 0 x q/r2 and v=1/4 0 x q/ rthis gives for same charge

E1/r2 V 1/rWhen we follow electric field line due to positive charge, distance from

positive charge increases which cases to decrease electric field and

potential.

Q#3:How can you identify that which plate of a capacitor is positively

charged?Ans#3:

When a freely suspende`d positively charged gold leaf of

electroscope is 8brought near to one of the plates of capacitor the

divergence to gold leaf shows that the plate of the capacitor is positivelycharge d otherwise negatively charged..

Q#4:

Prepared By:

Asif Rasheed BS(Hons) PhysicsContact# 0344-7846394,0323-7690026

1


2/23


Describe the force or forces on a positive point charge whenplaced between parallel plates,

(a) With similar and equal charges.(b) With opposite and equal charges.

Ans#4:The electric force F on a charge q due to eclectic field E is given by

F= qE(A) When a positive point charge is placed between parallel plates with

similar and equal charges. it will experience no electric force because

electric field between the plate is zero . F=qE

F=q(0) =0 F=0(B) When a positive pint charge is placed between the plates of the

Scapacitor it will experience electric force , F=qE S

Due to electric field set up from positive to negative .

Q#5:

Electric lines of forces never cross each other. Why?Ans#5:No, two electric lines of forces never cross each other because E

only one direction at a given point .if two lines cross each other then there

will be more directions at a point which is impossible.Q#6:

If appoint charge q of mass m is released in a non uniformelectric field with field lines pointing in the same direction, will it makea rectilinear motion?Ans#6:

Motion along a straight line is called rectilinear motion when acharge q of mass m is released in a non uniform electric field. It will

not move in a straight line and adopts irregular path due to variable electric

field.

Prepared By:


2


3/23


Q#7:Is E necessarily zero inside a charged rubber balloon if balloon is

spherical? Assume that charge is distributed uniformly over thesurface ?Ans#7: Yes E is necessarily zero inside a charged rubber balloon if balloonis spherical and enclosed no charge but chage is distributed uniformly over

its surface. According to Gausss law.

e=q/0=0/ 0=0 e = 0 --------1

From definition, e = E.A--------2Putting equation 1 in eq 2 0= E.A A # 0 so, E=0Q#8:

Is it true that Gausss law states that the total number of lines offorces crossing any closed surface in the outward direction isproportional to the net positive charge enclosed within surface?Ans#8:

Yes, it is true that total no of lines of forces crossing any closed

surface in outward direction proportional to the net positive charge

according with surface in the outward direction proportional to the net

positive charge enclosed with in the surface .According to Gausss law,

e=q/0 = constant x q

e q hereq = net positive charge .

e =no of electric lines of forceHence no of electric lines of forces are proportional to net positive charge

Q#9:Do electrons tend to go to region of high potential or of low

potential?Ans#9:

Prepared By:


3


4/23


Electrons tend to go to a region of high potential because high

potential is more positive than the lower potential as the charge on electron

is negative.

CHAPTER # 13QUESTIONS AND ANSWERS:-Q#1: A potential difference is applied across the ends of a copper wire.what is the effect of drift velocity(1) Increasing the potential difference.(2) decreasing the length and the temperature of the wire.Ans#1

The uniform velocity that the free electrons acqure opposite to the

electric field of battery is called the drift velocity.(1) the increase of potential difference makes the electric field strong

which cases to increase the drift velocity

(2) the decrease in length an temperature of the wire which causes to to

increase the drift velocity of the free electron in the wire.

Q#2:Do bends in wire effects its electrical resistance?

Ans#3We know that R= l/A with bends in a wire , its length (L) and area

of cross section (A) remains the same .hence bends in a wire do not affect

the electrical resistance (R) of the wire .Q#4:

Why does the resistance of a conductor rise with temperature?Ans#4

As temperature of the conductor rises the irrational amplitude of the

atoms of the conductor increases and hence the probability of collisions of

free electrons with them increases .at high temperature , the atoms offer a

bigger target area to free electrons to collide with them and resistance of

conducer

Prepared By:


-

--

4


5/23


increases.

Q5#:What are the difficulties in testing whether the filament of

lighting bulb obeys ohm law?Ans#5

At the beginning, when bulb is turned ON its filament is at low low

temrature and it obeys Ohms law. I V

Later on when current rises to its maximum value .the maximum power

P=I2R dissipated across the filament which increases resistance but current

increases at lower rate and does not obey ohms law

Q#6:Is the filament resistance lower or higher in a 500W, 220V light

bulb than in 100W, 220V bulb?Ans#6

Resistance of 1st bulb= R1=?Resistance of 2nd bulb =R2=?

Power of first bulb =P1=500 watts

Power of 2nd bulb=P2=100 watts

Voltage =V=220 volts

By applying the formula, P=V2/R R=V2/P

For1st bulb = R1=V2/P1 (220)2/500 = 48400/500 = 96.8

For 2nd bulb =R2=V2/P2 (220)2/500 = 48400/100 = 484

Q#7:Describe a circuit which will giva a continuously varying

potential?

Ans#7Potentiometer is an instrument which gives continuously varying

potential. Its circuit diagram is given as. When the sliding contact C is

Prepared By:


5


6/23


moved from A to B ,r

varies from O to R and potential varies from O to E the current following

through is given by ; I=E/R 1)The potential drops across

r is given by V=Ir as I=E/R soV=E/R xr V= r/R E 2)This gives us continuously varying potentialQ#8:

Explain why the terminal potential difference of a batterydecreases when a current drawn from it is increased?Ans#8

The terminal potential difference is given by /

Vt= E Ir 1)

The emf E of cell is constant .when current I through is increases ,theproduct Ir increases which cases to decrease the the terminal potential

difference Vt.

Q#9:What is the wheat stone bridge? How can it be used to determine anunknown resistance?Ans#9

An electrical circuit devised by Professor Charles Wheatstone used

to determine unknown resistance is called wheat stone bridge.It consists of four resistances R1, R2, R3, and R4. Connected in the formofmesh ABCDA . a battery of emf E is connected between points A and C

through a switch S .a sensitive galvanometer is of resistance Rg is

connected between points B and D.

Its equation is , R1/R2 = R3/R4 .1)

Prepared By:


6


7/23


Determination of unknown resistance:To determine unknown resistance in the arm containing R4 (R4 =RxThen known value of R1, R2. And R3are so adjusted that galvanometer no

deflection .then from equation no iR1/R2 = R3/Rx x = R2/R2 x R3

Chapter #14Q#1

A plan conducting loop is located in a uniform magnetic fieldthat is directed along the x-axis .for what orientation of the loop is theflux a maximum?. For what orientation is the flux a minimum?

Ans#1:When plane of loop is placed perpendicular to the magnetic field the

flux will be maximum e = EAcos0 = EA (max)

When plane of loop is placed parallel to the magnetic field, the flux will be

minimum as, e = EAcos90 = 0 (min)

Q#2A current in a conductor produces a magnetic field, which can

be calculated using Amperes law. Since current is defined as the rat offlow of charges, what can you conclude about the magnetic field due tostationary charges? What about moving charges?Ans#2:

Magnetic field due to stationary charges is zero. Moving charges

produce magnetic field around them.

Q#3Describe the magnetic field inside a solenoid carrying a steady

current I if (a) the length is solenoid is doubled but the number ofturns remains the same and (b)the number of turns doubled but thelength remains sameAns#3:.

The magnetic field due to solenoid is given by ,B = 0 n I As n = N /l so.B = 0 (N/l )I

Case #1:If the length is double and N remains the same .

Prepared By:


7


8/23


B = 0 (N/2l )I = 1/2 0 (N/l )I = 1/2 B

Which means magnetic field reduce to half

Case #2:If the number of turns (N) is double and l remains the same.

B = 0 (2N/l )I = 2 0 (N/l )I = 2 B

Which means magnetic field increases to two times?

Q#4At a given instant the proton moves in the x direction in a region

where there is magnetic field in the negative z direction. What isdirection of the magnetic force? Will the proton continue to move thepositive x direction ? ExplainAns# 4:

If proton moves along the positive x axis in a region of magneticfield is along negative z axis .the magnetic force is given by R.H. rule ,

Fb = q(v x B) , this force(Fb) is along the positive Y- axis and it will be

start to move in circular path in xy plane around z axis and it will not

continue to move in the positive x direction.

Q#5Two charged particles are projected into a region where there is

a magnetic field perpendicular to their velocities. If the charges arereflected in opposite directions, what can you say about them?Ans#5:

Two charge particles are projected in a magnetic field perpendicular

to its their velocity and they are deflected in opposite directions. As we

know that in magnetic field particles are deflected so they are oppositely

charged .So, one particle is positively charged and other is negatively

charged.Q#6

Prepared By:


8


9/23


Suppose that a charge q is moving in a uniform magnetic fieldwith a velocity v. Why is there no work done by the magnetic force thatacts on the charge q?-Ans#6:

A charge q is moving in uniform magnetic field B, with a velocity V

in a

Circular path due to magnetic force. The angle between

magnetic force and velocity will be 900 .work done is given by ,

W = F.d = Fd cos 900 =0 (as cos of 900 is zero).

So work is being done .

Q#7

If a charged particle moves in a straight line through someregion of space, can you say that the magnetic field in the region iszero?Ans#7:

No, when a particle moves in straight line in the direction of

magnetic field. B

. q o v

The force acting on charge will be zero as angle is 0 0 charge q and

magnetic field is parallel so,F= qvBsin00 = qvB(0) = 0

Therefore we can not say magnetic field in this zero.

Q#8

Why does the picture on TV screen become distorted when amagnet is brought near the screen?Ans#:8

As the picture is formed on the TV screen due to the electrons , when

a magnetic is brought is near the TV screen ,the beam of electron is

deflected due the magnetic force which is given by, F= evBsin0 .on the

each electron.

Q#9Is it possible to orient a current loop in a uniform magnetic field

cush that the loop will tend to rotate? Explain.

Prepared By:


9

90o

F


10/23


Ans#9The torque acting on a current carrying loop in the uniform magnetic

field is given by,

(torque )=NIABcos ,Where is the angle between B and plane of

loop .if = 900 then cos of 900= 0 so torque will be zero here this shows that

if plane of loop is oreintted at 900 with B .Then loop will not tend to rotate.

Q#10How can a current loop be used to determine the presence of a

magnetic field in a given region of space?Ans#10:

When current carrying loop is placed in the presence of a magnetic

field with its plane makes an angle with B .The torque acting on it will be

(torque )=NIBAcos if current loop deflects , filed is present other wise

not.

Q#11How can you use a magnetic field to separate isotopes of

chemical element?Ans#11:

When isotopes of chemical element are projected in a magnetic field

at right angle. then magnetic force ,

Fb= evBsin90 = evB

Provide centripetal force , Fc = mv2/r

Bev = mv2/r r= mv/Be

Isotopes has same charge , but due to different masses they adopt different

paths due to which fall at different places and are separated .

Q 12:What should be the orientation of a current carrying coil in a

magnetic field so that torque acting upon the coil (a)maximum (b)minimumAns#12:

When the current carrying wire placed in the uniform magneticfield . the torque acting on it is given by,

(torque )=NIBAcoswhere is the angle between and plane of the coil

Prepared By:


10


11/23


(a) when plane of the coil is oriented parallel to to B .then

=0 and cos0 = 1 so, (torque )=NIBA(1) = NIAB(max) =90and cos 90 = 0 (torque )=NIBA(0) =0at this the torque will be minimum.

Torque will be maximum

(b) when plane of coil is oriented at right angle to B then angle will be 90

so,

Q#13A loop of wire is suspended between the poles of a magnet with

its plane parallel to the pole faces. What happens if a direct current uisput through the coil? What happens if an alternating current is usedinstead?Ans#13:

Torque on loop wire is given by , (torque )=IBAcos

When the loop of wire is suspended between the poles of a magnet with itsplan parallel to pole faces then =90 and cos 90 = 0 then we get theresult

(torque )=IBAcos90 =0if direct current or alternating current is passed through the coil .these

current have no effect on the loop

Q#14Why the resistance of an ammeter should be very low?

Ans#14:Ammeter is always connected in series the magnitude of current

decreases through through the circuit with the presence of ammeter .to

measure

I Rmaximum current the resistance of ammeter should be very small as

compared to the resistance of circuit.

Ans#15:Why the voltmeter should have a very high resistance?

Ans#15:Voltmeter is always connected I in parallel with two points where

potential is to be measured. the potential across the points decreases with

presences of voltmeter because it draws some current Iv of the circuit . to

Prepared By:


11


12/23


reduce the current through voltmeter ,the resistance of voltmeter should be

large as compared to the resistance of circuit .

A IR R B

CHAPTER # 15

Q#1Does the induced emf in a circuit depend upon the resistance of thecircuit?Does the induced emf depends upon the resistance of the circuit ?Ans#According to Faradays law .emf is given by

=-N / tThis relation shows that emf induced in coil depend upon the rate of change

of magnetic flux and does not depends on the resistance of the coil .

While in case of ohm law induced current flowing through coil depends

upon the resistance R, of the coil

I= /RQ#2

A square loop of wire is moving through a uniform magnetic field. Thenormal to the loop is oriented parallel to the magnetic field. Is emfinduced in the loop ? Give a reason for your answer?

Ans#2. B

. A v

E= VBLsin0

If the vector area is parallel to B . then according to faradays law the timerate of change of flux becomes zero. / t=0 for N=1

=-N / t = -1 X 0=0Hence there is no emf produced in a loop

Prepared By:


12


13/23


Q#3A light metallic ring is released from above into a vertical bar magnet.Viewed for above, does the current flow clockwise or anticlockwise inthe ring?Ans#3According to lenss law the direction of induced current will oppose the

motion of ring towards the bar magnet .for this purpose, the induced current

should flow in the clock wise direction the ring.

Q#4What is the direction of the current through resistor R in fig.? whenswitch S is

(a) closed(b) opened

Ans#4

a) As the switch is closed, according to lenss law, the direction ofcurrent induced in R will be in anti clockwise direction.

b) A switch S is opened according to lenss law the direction of current

induced in R will be in the clock wise direction

Q#5Does the induced emf always act to decrease the magnetic flux througha circuit?Ans#5

No, induced emf does not always act to decrease the magnetic flux through

the circuit .according to lenss law ,when bar magnet with N pole is moved

towards a loop flux decreases and when it taken away from a loop flux

increases which case emf induced.

Q#6When the switch in the circuit is closed a current is established in thecoil and the metal ring jumps upward (fig.) why?Describe what would happen to the ring if the battery polarity werereversed?Ans#6When switch S is closed, the changing flux of coil causes to induce current

in the metal ring which produces flux opposite to that of coil and ring isreplaced and jumps upward. Same thing will be happen if polarity of the

battery is reversed.

Q#7

Prepared By:


13


14/23


The fig. shows a coil of wire in the xy plane with a magnetic fielddirected along the y axis.Around which of the three coordinate axes the coil should be rotated inorder to generate an emf and a current in the coil?Ans#7The coil must be rotated about about x-axis to get change of magnetic flux

and an induced current through it.The emf induced in the coil is given by

=NwABsin0 .only in this case emf is induced.

If the coil rotated about z-axis then no change of magnetic flux takes place .

If coil rotated through y-axis then the flux through it will be zero.b/c plane

of the coil is at all times parallel to the lines of magnetic field

Q#8How would you position a flat loop of wire in a changing magnetic field

so that there is no emf induced in the loop?Ans#8Induced emf is given by ,

=NwABsin0N=1 so, =wABsin0

As flate loop of wire is parallel to changing magnetic field then =00

=wABsin00 = 0 this shows that nom flux change through it and hence noemf is induced.

Q#9In a certain region the earths magnetic field vertically down .when aplane files due to north, which wingtip is positively charged?Ans#9The magnetic force on a moving electric charge is given by ,

F = -e (V X B).

this relation shows that F acting at right angle to v is towards north B is

vertically downward ,the electron moves towards left

N direction of F is directed towards west .

w ES

Q#10Show that and e/t have same units?

Prepared By:


14


15/23


Ans#10 = W/q as unit of work is joule and charge is coulomb so, = J/C = JC-1 = volt a)Hence the unit of is volt.

Unit of / t is ---------b)

= BA = NA-1m-1 m2

t = sec

Then b ) becomes ,

/ t = NA-1m-1 m2/s

/ t = N m/A s As N m =J, A s = coulomb = C

/ t = J/C = volt

Q#11When an electric motor, such as an electrical drill, is being used, does italso act as a generator? if so what is consequences of this?

Ans#11When an electrical motor is running, its armature is rotating in a magnetic

field. a torque acts on the armature and at the same time magnetic flux is

changing through is changing which produced an induced emf .the induced

emf opposes the rotation of armature .this means that motor also act as

generator when it is running .when motor rotate without load it will rotate

quite easy,then large back emf is induced .but in case of when motor is over

loaded the induced back emf in the coil produces high current which cause

to burn the motor out .

Q#12Can a D.C motor be turned into a D.C generator? What changes arerequired to be done?Ans#12Yes,

D.C motor and D.C generator are same in construction but the difference is

that D.C is mechanically driven instrument while D.C motor is electrically

driven.

If voltage is supplied by connecting a battery to slip ring of D.C generator,

then D.C generator acts as D.C motor.

When current passes through armature of motor a torque is produced whichrotates the armature .by converting electrical energy into mechanical

energy .thus a D.C motor can be converted into D.C generator.

There are two changes occurs to convert D.C motor into D.C generator

Prepared By:


15


16/23


1) The magnetic field must be applied by permanent magnet and

not by electromagnet.

2) An arrangement to rotate the coil armature should be

provided.

Q#13Is it possible to change both area of the loop and the magnetic fieldpassing through the field and still not have an induced emf in the loop?Ans#13Yes, it it is possible in the magnetic flux takes due to the change in the area

of the loop and magnetic field, no emf will be induced in the loop.

Magnetic field is given by .

= B . A =Bcos

if the vector area A is parallel to magnetic field B.

= 00 so,

=BAcos00 cos0=1 =BA

if b B and A are constant then , =0

=-N/t

=-N X 0/ t =0

Hence no induce emf in the loop will be produced

Q#14Can an electric motor be used to driven an electric generator with theout put from the generator being used to operate the motor?Ans#14

No, it is impossible .if it is possible it will be self operating system without

getting energy .which is against the law of conservation of energy.

Moreover the efficiency is always less than 100.

Hence a combination of motor and generator can never produce more

energy out than its energy.

Q#15A suspended magnet is oscillating freely in a horizontal plane. Theoscillations are strongly damped when a metal plate is placed underthe magnet. Explain why this occurs?

Ans#15The oscillating magnet produces change of magnetic flux close to it. Themetal plate below it experience a the change of magnetic flux .As a result

eddy current produced inside the metal .according to lenss law ,

Prepared By:


16


17/23


Eddy currents oppose the cause which produces it. Therefore ,the

oscillations of magnet are strongly damped.

Q#16Four unmarked wires emerge from a transformer. What steps wouldyou take to determine the turns ratio?Ans#16Four wires coming out of transformer are the ends of two coils (p&s) of

transformer .each coil has negligible resistance for D.C .the coils are

separated as primary and secondary. an alternating voltage of known value

vp to the primary coil the output voltage across the secondary coil. The turn

ratio of the coil is determined as,

Vs/Vp =Ns/NpQ#17

a) Can a step up transformer increases the power level?

b) In a transformer, there is no transfer of charge from the primaryto secondary .How is then the power transferred?

Ans#17a) No, a step up transformer can not increase the power level. the power

of out put is always less than input. in ideal case input is equal to the

out put.

b) Two coils of transformer are magnetically linked, the change of flux

through one coil is linked with the other coil and emf is produced.

Q#18When the primary of a transformer is connected to a.c mains the current in

it,a) is very small if the secondary circuit is open ,but,b) Increases when the secondary circuit is closed .explain these

facts.Ans#18

a) if the secondary circuit is open, then out power will be zero .because

out put power always les than input power .therefore very small

value of current is being drawn by a primary coil of transformer a.c

mains

b) When the secondary circuit is closed, the out power will beincrease .therefore the transformer will draw a large current from the

a.c mains to increase the primary power.

Prepared By:


17


18/23


GUESS PAPERS FOR 2ND YEAR PHYSICS

PHYSICS CH# 12Q#1:

Electric lines of forces never cross each other. Why?Q#2:

Do electrons tend to go to region of high potential or of lowpotential?Q#3:

Is E necessarily zero inside a charged rubber balloon if balloon isspherical? Assume that charge is distributed uniformly over thesurface?Q#4:

How can you identify that which plate of a capacitor is positively

charged?

PHYSICS CH # 131) If last band is not silver not gold then tolerance------

a) 0 b) 10 c) 20 d) 302) A complex system consisting of number of resistor is solved by ----

a) Joules law b) Ohms law c) coulombs law d) Kirchhoff, s law3) in metals the current flow due to the motion of

a)electron b) proton c) holes d) both a and b4) the unit of electromotive force is ------

a) J b) C c) N d) V5) The colour code usually consist of ---------

a) Infinite band b) 2 band c) 3 band d) 4 band6) During the electrolysis process, density of CuSO4 -----

a) Increases b) decreases c) remains constant d) non of these7) The liquid which conduct electricity is called, ------

a) Insulator b) conductor c) electrolyte d) both a&b8) The drift velocity of electrons is

a) 103m/sec b) 10-3m/sec c) 106m/sec d) 10-6m/sec9) Rheostat ct as ----

a) Variable resistor b) source of current c) potential divider d) both a&c

Prepared By:


18


19/23


10) Four similar wires of each resistance 20 attached to form squre then the

resistance between two corners is-----

d) a) 0 b) 10 c) 20 d) 4011) Why the resistor add in series ---

a) Divide the voltage b) increase the the voltage c) decrease the voltage d)non

12) If a 40 watt light bulb burns for 2hours, how much heat is generated

a) 388x103J b) 288X103J c) 60J d) 90J

Q#1:Do bends in wire effects its electrical resistance?

Q#2:Why does the resistance of a conductor rise with temperature?

Q#3:What is the wheat stone bridge? How can it be used to determine anunknown resistance?Q#4:

Describe a circuit which will giva a continuously varying potential?

PHYSICS CH #141) The unit of magnetic flux is----------

a) Weber m+2 b) Weber m-2 c) Tesla d) Weber2) A galvanometer is converted into an ammeter by connecting a

suitable-------

a) Low resistance b) high resistance c) comparing voltage d) non ofthese

3) The magnetic induction is also called -----

a) Flux density b) magnetic intensity c) flux d) electric intensity4) Which of the following is scalar quantity ------

a) emf b) flux density c) magnetic flux d) a & c5) The working of a galvanometer depends upon

Prepared By:


19


20/23


a) material of the coil c) magnetic force exerted on the coil d) mass of

coil b) torque exerted on the coil6) a current flowing towards the reader is denoted by the symbol -----

a) Cross b) dot c) a& b d) non of these

7) the radius of an obit of an electron moving at the rate of 9.3 x 106

m/sec in a uniform magnetic field of 3.5 x 10-2 T IS

a)1.51x10-2m b)1.17x103m c)1.51x10-3m d) non8) Which of the following quintiles does not effected by magnetic

field

a) Moving charges b) stationary charges c) charge in the magneticflux d) current in conductor

9) a magnetic needle placed in a non uniform magnetic field

experiences.a) only torque b) only force c) no effect d) both a&b10) AVO meter is used to measure a---------

a) Resistance b) voltage c) current d) all of these11) Total number of lines of magnetic induction passing through any

surface placed perpendicular to the field is called ----

a) Magnetic induction b) magnetic flux c) flux density d) flux12) A charge particle moving at right angle to the magnetic field will

experience ---a) Minimum force b) maximum force c) zero force d) non of these13) Two wires carry current in the same direction ---

a) Attract each other b) repel each other c) remains same d) nonQ#1: Why does the picture on TV screen become distorted when a magnet is

Brought near the screen?Q#2

How can a current loop be used to determine the presence of a

magnetic field in a given region of space?Q#3:Why the resistance of an ammeter should be very low?

Q#4:

Prepared By:


20


21/23


Why the voltmeter should have a very high resistance?Q#5:

How can you use a magnetic field to separate isotopes of chemicalelement?

Q#6:If a charged particle moves in a straight line through some region ofspace, can you say that the magnetic field in the region is zero?

PHYSIC Ch#15Tick the correct answer

1) The fact that eclectic current produces magnetic field was discovered

by____

a) Michel faraday b) Hens arrested c) Henry d) Amperes2) The current produced due to the phenomena of electromagnetic

induction is called___

a) Positive current b) Negative current c) Conventional current d)Induced current

3) Lens law deals with the__

a) Magnetic field of emf b) Direction of emf c) Direction ofinducedcurrent d) All

4) The SI unit of mutual induction is__

a) Vsec/A b) VA/sec c)A/Vsec d) V5) Identify which one is not the main component of an A.C generator

a) Armature b) Magnet c) Slip rings d)Commutatotr6) For a motor which is over loaded the magnitude of back emf ___

a) Becomes zero b) Get decreased c) Increased d) Remainsconstant

7) The magnetic flux linked with a coil varies at the rate of 10Wb/min,

the induced emf is___

a) 1/6 V b) 10V c) 6V d) 8V8) If the magnetic flux is doubled in an inductor then the energy

density ____

a) Double b) Half c) Four times d) Remains constant9) If the velocity of the conductor moving through a strong magnetic

field is zero

Prepared By:


21


22/23


then motional emf is__

a) D.C generatorb) D.C Motor c) A.C Generator d) All of these10) The magnet falls with its S-pole along the axis of a ring the

current generator is

_____ and acceleration is____

a) Clock wise, >g b) Clock wise, g D)Anti clock

Wise,


23/23


a) lag the voltage by 900 b) lead the voltage by 900 c) lead the voltage by 1800 d) lag the voltage by 1800

6) The chock coil is used to control------

a) A.C b) D.C c) both a&b d) non of these7) At high frequency of A.C ,the capacitive reactance----

a) Remains constant b) increases c) decreases d) zero8) The impedance at resonance frequency of series RLC

circuit,C=0.015F

R=80

a) 50 b) 80 c) 100 d) 1509) The average value of A.C and voltage over a complete cycle is ----

a)0.707times b) zero c) maximum d) minimum10) Shake an electrically charged object to and fro produces.

a) Transverse wave s b) sound waves c) electromagnet waves d)

non11) Maximum of sound wave with electromagnet wave is called ----

a) Modulation b) choke c) frequency d) a&b12) in free space the speed of electromagnetic waves is----------

a) 3x 108ms-1 b) 3 x10-8ms-1 c) 2.99 x 10-8ms-1 c) varying with timeQ#1:

A sinusoidal current has rms value of 10 A. what isMaximum value or peak value?

Q#2: In a R-L circuit, will the current lag or lead the voltage?

Illustrate your answers by vector diagram.Q#3:

Explain the conditions under which electromagnetic wavesAre produced?

Prepared By:


23

2nd Physics Short Ans + MCQ

Documents