Waec 2017 Physics Obj And Theory Answers – May/June Expo

WAEC (Physics) ANSWER

*Complete Physics obj*

1-10 CAABADACC

11-20 BAADDCBADA

21-30 CCBACBCBAB

31-40 ACADDBBBAC

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(i) / means division or divide

Examples:2/2 means 2/2 ie 2 over 2.—————–

(ii) * means multiplicationExample: 

2*2 means 2×2—————–(iii) ^ means Raise to power—————–

(iv) Sqr root means means square root sign ie _/

1)decrease in height 

(h)increase in time 

(t)this shows that distance changes with time============

2)given that U=15m3^-1R=U* sqr2h/gh=20mg=10R=15*sqr2*20/10R=15*sqr40/10R=15*sqr4R=15*2=30mR=30m=

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3)i)Brownian motionii)Atomic sizeiii)Expansion==========

=4)L1=14cm F1=4N,F2=6NL2=4cm, Lo=?Using hooke’s law4/14-Lo*6/4-Lo4(4-Lo)=6(14-Lo)16-4Lo=64-6Lo-4Lo+6Lo=64-162Lo=48Lo=48/2Lo=24Cm============

5a)i)forceii)length

5b)by increasing the density mosquitoes lavrva thanthe density of water==========

=6)A)Energy efficient- so far the best light for interior lightingB)Low production cost (of tubes, not of the ballasts)C)Long life of tubes===========

7)i)It requires low voltage sources for it to functionii)It cannot be easily brokeniii)It is cheaper and quite easy to manufacture===========

8a)i) It is a straight line graphii) The gradient is the velocity

8b)If their distance and masses are doubled their corresponding force would also be doubled and the work done respectivelyI.e.Workdone=Force * distanceForce= Mass * AccelerationW= Mg * d|Increase

8c)-Acceleration due to gravity– At maximum height, final velocity is zero

8d)i)pushing someone on a swing.ii)Tuning a radio to a particular frequency.============

10a)A wave front is an imaginary surface passing through the points of a medium oscillatory in phase

10b)i)Priam periscope used in harmod carii)prismatic bihocular to see round corner

10bii)i)refractive indege of the glass prismii)the angle of incident of the roy==========

11ai)A dielectric is an electrical insulator that can be polorised by an applied electric field.(11aii)Given that A = 9.6*10^-3M^2d = 2.25*10^4Eo = 8.85*10^-12 F/mEr = 900C = /using; C = EoErA/dCapacity, C = 8.85*10^-12*900*9.6*10^-3/2.25*106-4C = 33984 * 10^-11C = 3.3984 8 10^7 FC =0.34#F

11bii)Combined resistance RTRT= (400*400)/400+400 = (800*800)/(800+800)RT= 200+400RT =600 ohmsCurrent supplied by battery = v/RT= 6/600=0.01AVoltage drop across 400 ohm resistors= 200*0.01=2vTherefore the voltmeter reading is= 6 – 2= 4v

(11c)Equivalent resistance is:RT = 2+2 +(2*2)/2+2RT = 4+1RT = 5 ohms===========

=12ai)Nuclear fission is a nuclear reaction in which a heavy nucleus splits spontaneously or on impactwith another particle, with the release of energy.

12aii)a)A graphite reactor is a nuclear reactor that uses carbon as a neutron moderator, which allows un-enriched uranium to be used as nuclear fuel.b)Boron rods are used in nuclear reactors to control the fission rate of uranium and plutonium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.c)Liquid sodium serves as coolant in a nuclear fission reactor.=

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