Danyal Education Danyal Education Static Electricity ... ?· Unit 10 Static Electricity and Curuent…

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  • Unit 10Static Electricity andCuruent Electrici

    Multiple-choice Qrestions

    l. M, N, O and P are pith balls which behaves asfollows:

    M repels N;M attracts O andO repels P.

    If P is positively charged,A N must be positively chargedB N must be negatively chargedC N must be positively charged or neutralD N must be negatively charge or neutral (

    2. A charged sphere at Y experienced a force of3 N to the right when it is placed between the twocharged plates as shown.

    What is the type of charge on Y and what is theforce acting on it when it is moved to the middleof the two plates?

    Charge onY Force exerted onYA Positive 3 NB Negative 3 NC Positive 4.5 ND Negative 4.5 N

    ()

    3. An uncharged sphere X and an identical butpositively-charged sphere Y are suspended frominsulating threads. Which of the following figuresbest shows what happens when they are placednext to each other?

    4. What will happen if a positive charge is placed inan electric field?A A force will be produced on the charge.B The charge will become negative.C The charge will remain positive but become

    smaller.D The charge will remain positive but become

    larger. ( )

    5. The diagram shows a light positively-chargedspherical conductor X suspended in between twoinsulated copper spheres, P and Q, which areconnected to a d.c source.

    C D

    XY X)(

    X)(

    E.H.T+

    When the switch is closed, X will

    -.

    A move to Q and stayB move to P and stayC move to Q then oscillate between P and QD moves to P then oscillate between P and Q

    ()

    XY XY

    A B

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    DanyalText BoxDanyal EducationStatic Electricity Assignment 2 (Combined)Current Electricity Assignment 2 (Combined)

  • 6. A positively-charged pith ball attracts anothersuspended pith ball. Which of the followingstatements about the second pith ball is correct?A It must have fewer positive charges.B It must be negatively charged.C It does not need to be charged.D It must be earthed. ( )

    7. M and N are two spheres given the same quantityofelectric charge. P is a point equidistant from Mand N.

    B

    C

    In which direction (A, B, C or D) does the electricfield act on a positive test charge at the point P?

    ()

    8. In a given circuit, the current is 0.32 A. If thecharge of an electron is 1.6 x lO-teC, how manyelectrons will flow past a fixed point in the circuitin one second?A lxl0r8 B 2x1018C 5x10'8 D 8xl0r8 ( )

    9. An ebonite rod is rubbed with fur and the rodbecomes negatively charged becauseA the fur has lost some electrons to the rodB the rod has gained some electrons from the furC the fur has gained some protons from the rodD the rod has gained some protons to the fur

    ()

    10. The diagram shows a small conducting ballhanging on an insulating thread near to a chargedmetal plate. If the sphere is given a positivecharge, it

    A moves away from the plateB remains stationaryC is attracted to the plate and sticks to itD is attracted to the plate and is then repelled

    byit ( )

    I 1. If W and Y exert no force on each other, U and Xrepel each other, while all other pairs attract eachother, we can conclude thatA Y is neutralB W is negatively chargedC U and X are positively chargedD Y carries a charge which is opposite to that

    ofU ( )

    12. An uncharged conductor is placed between twooppositely charged parallel plates as shown.

    +

    Which of the following diagrams correctlyrepresents the fleld pattern inside the space betweenthe plates?

    A + B

    A

    P

    DNM

    C D

    ()

    13. The diagram shows an uncharged conductorplaced between two oppositely charged parallelplates.

    +++++

    Which of the following diagrams representcorrectly the field pattern in the space betweenthe two plates?

    nylon thread

    I

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  • \/,

    14. When an ebonite rod is rubbed with a duster, therod becomes negatively charged. Why is this so?A The duster gains protons from the rod.B The duster loses electrons from the rod.C The rod gains protons from the duster.D The rod loses electrons from the Ous,"t

    , ,

    15. When a positively-charged rod is brought nearbut not touching an earthed spherical conductor,

    A the conductor will not be charged since it isearthed

    B the conductor will be charged positivelyby positive ions from the air being repelledtowards it

    C the conductor will be charged negatively byrepulsion of the protons to the Earth

    D the conductor will be charged negatively byelectrons being attracted from the Earth

    ()

    16. In which direction does the electric field act at thepoint P between the two charges shown?

    P D

    11 . X and Y are two light metal balls suspended usingnylon thread. When a positively-charged rodwas placed between these two balls, ball X wasattracted towards the charged rod but ball Y wasrepelled away from the rod.

    ++attracted

    Which of these is the correct conclusion aboutthe charge on each ball?

    Ball X Ball YA negative only positive onlyB negative or neutral positive onlyC negative only positive or neutralD negative or neutral positive or neutral

    ()

    18. A negatively-charged rod is brought near to thecap of a charged gold-leaf electroscope. The leafof the electroscope willA rise a little furtherB fall a littleC stay in the same positionD rise or fall depending on the charge ofthe

    electroscope ( )

    19. Three different rods were charged by rubbing. Thefollowing observations were made on bringingeach rod close to the others: rod I repelled rod2, rod I attracted rod 3. Which of the followingcould be the arrangement of charges on the rods?

    Rod 1 Rod 2 Rod 3A++B+-C+D()

    A B

    C D

    (

    +++++

    +++++++

    T5--4repelled

    B

    C

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  • 20. The lower part of a cloud has a positive charge. 23The cloud discharges in a flash of lightning.

    In which direction do electrons and conventionalcurrent flow?

    Electrons CurrentA downwards downwardsB downwards upwardsC upwards downwardsD upwards upwards ( )

    21. The resistance of a length of wire is R Q. Whatis the resistance of a wire of the same material,of length which is twice as long but with half thecross-sectional area?A RI4BRC2RD4R ( )

    22. The diagram shows a popular type of a rearwindow heater consisting of four identical heatingelements. It operates at lzY and carries a currentof4A.

    12 V d.c. supply

    What are the voltage across and the current throughONE element?

    Voltage in volts Current in amperesA3483lct2 IDt24()

    Which circuit would be suitable for measuringthe resistance of a lamp?A rl

    rl

    D

    B

    C

    24. A cell of e.m.f. 3.0 V passes a current of 1.0 Athrough an external circuit for I minute. If thecell has an internal resistance of 0.5 Q, how muchenergy is lost from within the cell in joules?A30 860c90 Dl80 ( )

    25. The heating element of an electric iron takes acurrent of 2.0 A from a 250 V supply. What isthe rate of production of heat in the element inwatts?A t25 B s00c 1000 D 4000 ( )

    26. The resistance of wires X and Y areirr ratio of 2:7whereas their lengths and diameters are in theratio of 1.:2.The ratio of the resistivities of X :Y is

    B 1:2D 4:l

    ()

    ()A l:lC 2:l

    r\\\\\\\\\\\\r

    \\\\\\\\\\\T

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  • 27. The effective resistance between terminals P and [For Qrestions 29 and 30]Q in the circuit below is o.

    28. Which of the following resistor combinations hasthe highest resistance?A 3cl

    3O

    6()

    B 3A eJ

    6O 6f)

    3() 6()

    6c2

    The diagram below show four identical lamps connectedin series with the mains.

    4.0 A

    240 V mains

    29. The voltage marked on the lamp is

    -.A 3OV B 6OVc l20v D 24oY ( )

    30. The power rating of the lamp is

    oP

    O

    A15c30

    B20D40 ()

    A r20wc 480w

    B 240WD 960W

    31. Which of the following graphs shows therelationship between current 1, and voltage V, fora tungsten filament lamp?

    A/BI

    C DC

    0

    I

    (

    00

    )oD

    10a

    0

    I

    6O

    6O

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  • 32. The reading of the ammeter in the first circuit is3 A. In the second circuit, a resistor of 200 Q hasbeen added.

    a

    What is the reading of the ammeter in the secondcircuit?

    200 e2

    A 3AB slightly less than 3 AC slightly more than 3 AD about3OOA

    33. What is the relationship between the current, Iflowing through a metal of resistance of value R,and the potential difference, % across it?

    34. The diagram shows two 6 V,6 W lamps connectedtoal2Vbattery.

    XY

    35. What is the value of R if voltmeter V read 4 V?

    10v

    5() R

    36. In the diagram below, what are the readings of thevoltmeter V and the ammeter A?

    1() 2A

    6.0 v

    A 3.3QC 6.0Q

    Reading in AA 2.OAB 2.OAC 3.OAD 3.OA

    A 500c50

    B 5.OQD 7.5Q

    B 100D2s

    Reading in V2.0Y4.0 v2.0Y4.0 v

    ()

    (l

    rl

    A V=RIIB R=VIC V=IRD V=PR

    37. A dry cell of e.m.f. 3.0 V has a wire connectedto its terminals. If 12 C of charge passes throughthe circuit, what amount of chemical energy istransformed into electrical energy?A 0.25J B 3.6Jc4.oJ D36J ( )

    38. A dry-battery will deliver 3000 J of energy toa small 2-watt electric motor before the batteryis exhausted. The motor will stop running after

    minutes.

    t- I12V

    Whichof the following statements is NOTcorrect?A The ammeter reads I A.B Thetotalpowerdissipatedby thelamps is l2WC The voltmeter reads 6 V.D If the filament of the lamp Y breaks, the

    voltmeter reads zero. ( )

    2A

    -

    ()

    ()

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  • 39. Wires of various lengths and circular cross-sectional areas were made of the same material.If the lengths and diameters of the wires were asshown below, which of these would provide thehighest resistance?

    Length of wires/cm Diameter/mmA 1.0 2.0B 2.O 3.0c 3.0 1.0D 4.0 2.0

    ()

    40. Three resistors of resistance I Q, 2 Q and 3 Qrespectively are used to make the combinationsX, Y and Z shown in the diagrams.

    X2A 2A

    1()

    z3()

    Which of the following gives the combinationsin order ofincreasing resistance?A XYZ B XZYcYxz DZXY (

    41. Which diagram shows the I/V characteristic graphfor a conductor that obeys Ohm's Law?A/BI

    42. When a p.d. of 2 V is applied across a resistor,l0 J of energy are converted. What charge flowsthrough the resistor?A 0.20c B 5.0cc12C D20C ( )

    43. What is the resistance between X and Y?

    10o

    10()X

    44. Which of the following graphs correctly showsthe relationship between the resistance R of awire and its cross-sectional area A?

    A R/A B R/A

    A 15QC IOQ

    A 0.20 Ac 0.61 A

    B OQD 20{'

    A/cm2

    D

    A/cmz

    C FYO R/A

    A/cm2 A/cm2

    45. Three l0 S2 resistors were connected in a circuit asshown in the diagram below. What is the currentflowing through resistor P?

    10v

    +

    10a

    10()

    )(

    0 0

    ICI D

    n

    (

    0 P

    )B 0.33 AD I.OA

    nichrome wire

    10e2AIA

    1e2 3cl

    1e2 2a

    10o

    (

    3e)

    )

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  • 46. When a current of 2 A flows for 5 s through alamp, 120 J of energy are transformed. Howmuch charge flows through the lamp?A lOC B IzCc24C D60C ( )

    47. What is the reading on the voltmeter in the circuitbelow?

    100 v

    '100 ko

    300 ko

    OV

    48. What is the potential difference across the cell?

    10A 20eJ

    4.0 A

    A 44OYC I2OY

    B 22OYD 6OV ()

    A 25YC 5OV

    B 33VD IOOV ()

    49. The unit volt isA a flow ofone coulomb ofcharges per secondB adissipation ofenergyofonejoule in I secondC a dissipation ofenergy ofonejoule per unit

    ampere of current flowD a dissipation of energy of one joule per unit

    coulomb of charge flow ( )

    30()Da

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  • Short- structured Qrestions

    l. A battery of e.m.f. 20 V is connected in the circuit below, producing a current of 2.0 A in the 7 Qresistor.

    2.0 A 12A

    7A

    Calculate:(a) the potential difference across the 7 Q resistor,

    (b) the potential difference across the two resistors in parallel,

    (c) the current inthe 12 e) resistor,

    2OY tF--l

    (d) the resistance ofthe resistor R tslDany

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  • t---4.0 c2

    3.4 ()

    6.0 a

    2. The ammeters in the circuit shown below have negligible resistance.

    0.20 A

    Using the values shown, calculate

    (a) the current through ammeter A,

    (b) the reading of the voltmeter across the cells,

    (c) the energy dissipated in the 4.0 Q resistor in 2 minutes

    3. In the circuit below, the ammeter reads 3.0 A.

    3.0 A2A 4A

    ILt

    tzl

    t2)

    D

    1s,2ADany

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  • (a) Calculate the currents in the pathway (i) ABC and (ii) ADC. t2l

    (b) Calculate the potential differences between (i) A and B, (ii) A and D, and hence (iii) B andD. t3l

    4. (a) Calculate the readings of the voltmeter V andthe ammeter A in the circuit diagram. Find alsothe power dissipated in the circuit. t3I

    6e2

    4A

    3 O resistor

    (b) Explain, without detailed calculation, whether the reading of the voltmeter will increase ordecrease ifthe 3 f) resistor is now changed to a 6 Q resistor. t2)

    't2v

    (c) Why should voltmeters have as high a resistance as possible but ammeters as low a resistanceas possible? t2)

    Ir

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  • 5. The diagram shows a circuit consisting of a battery ofe.m.f. 6.0 V and four 3.0 f) resistors.

    State

    (a) the potential difference between K and M,

    (b) the potential difference between L and M,

    6:0_V_!-

    3.0 () 3.0 ()

    3.0 s, 3.0 a

    L

    (c) the potential difference between L and N

    6. The diagram shows part of a circuit. The current through the 3.0 Q resistor is 2.0 A.

    t3l

    t1l

    t1l

    121

    =2.0A 3.0o

    X

    4.0 o

    (a) What is the potential difference across the 3.0 Q resistor?

    (b) What is the potential difference across the 6.0 Q resistor?

    (c) What is the value of the current 1r?

    l1

    t^

    6.0 f2

    (d) What is the value of the current 1 ? tll

    I

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  • (e) What is the potential difference across the 4.0 Q resistor? t1l

    (0 What is the potential difference across XY? tll

    (g) What is the effective resistance between X and Y? t2l

    7. The diagram below shows a circuit consisting of a battery of e.m.f. 6.0 V and two pairs of 3.0 Qresistors in series, these pairs of resistors being connected in parallel.

    6V

    3.0 o 3.0 ()

    (a) (i) What is the total resistance of the path KLM? tll

    3.0 (2 3.0 o

    L

    MK

    N

    (ii) What is the total resistance of the path KNM? t1lDany

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  • (iii) What is the resistance of the circuit between K and M? tzl

    (b) Calculate the current through the battery t2l

    8. A type of electric toaster, designed to toast two slices of bread at the same time, has four identicalheating elements P, Q, R and S arranged in the circuit shown below. When connected to the mains,a potential difference of 240 V is applied across XY and a current of 2 A flows in each element.

    2A 2A

    2A o S 2A

    240V

    (a) Calculate the potential difference across element P. t1l

    (b) Calculate the resistance of element Q tlI

    (c) Calculate the electrical energy transformed by element Q each second. tl l

    X

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  • (d) Calculate the total energy used by the toaster in 2 minutes. tzl

    (e) What is the total current drawn by the toaster? tzl

    g. The diagram below shows an electric circuit in which the internal resistance of the battery isnegligible. The current supplied by the battery is 5.0 A.

    5.0 f,

    12V -

    (a) Calculate the current through resistor A. l2l

    (b) Calculate the resistance of resistor C t2)

    A 4.0 ()

    B

    c

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  • 10. (a) Define resistance and Ohm's Law t2)

    (b) In the circuit shown below, the ammeter reads 0.5 A.

    1c, 2A

    (i) What is the total resistance of the circuit? t3l

    (ii) What does the voltmeter read? tzl

    11. The graph shows the voltage/current characteristics of two wires A and B

    (a) Calculate the resistance of wires A and B. 12)

    VoltageA/ 1

    0.4CunenVA

    (b) Both the wires are made of the same material and have the same length. Which wire is thinner?Why? ttl

    0.3o.20.1

    4O

    ,y

    z

    100

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  • (c) What is the ratio of the cross-sectional areas of wire A and wire B? t1l

    (d) Wires A and B were then connected in series to a 1.5 V cell.Calculate(i) the combined resistance of A and B, t1l

    (ii) the current through A, t1l

    (iii) the voltage across A. tll

    12. The circuit shows a battery of e.m.f. 6 V andnegligible internal resistance, connected toother components. The reading of the ammeteris 0.5 A.

    Calculate(a) the potential difference across the 8 Q resistor,

    (b) the reading of the voltmeter,

    (c) the value of the unknown resistor, R,

    (d) the power dissipated in R.

    6VF-l

    R BO

    t6l

    10r

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