GreenHallAcademy
TestSession~2019-20 TotalMarks:30
Name:
Class:2ndyear
Date:31-December-2019
Test:Physics
Chapter:12(Electrostatics(Half))
TimeAllowed:1hour
MultipleChoiceQuestions(MCQ's).
Q1.Encircleortickthecorrectanswer. (1×8=8)
(i).Theelectrostaticforcebetweentwochargesis42N.Ifweplaceadielectricofε
r
=2.1betweenthecharges
thentheforcebecomeequalto:
(a)42N (b)84N (c)20N (d)2N
(ii).Seleniumis:
(a)insulatorindark (b)insulatorinlight
(c)conductorindark (d)semiconductorindark
(iii).Forthecomputationofelectricflux,thesurfaceareashouldbe:
(a)Flat (b)Curved (c)Inclined (d)Spherical
(iv).Ifthedistancebetweenthetwochargedbodiesishalved,theforcebetweenthem becomes:
(a)double (b)half (c)fourtimes (d)onefourth
(v).SIunitofstrengthofelectricfieldis:
(a)J/C (b)C/V (c)N/C (d)J/N
(vi).Whenareaisheldperpendiculartothefieldlines,thenthemagnitudeofelectricfluxis:
(a)maximum (b)minimum (c)either(a)or(b) (d)negative
(vii).Theunitofsurfacechargedensityis:
(a)coulomb (b)volt (c)coulomb/meter² (d)newton/meter²
(viii).Ifachargedbodyismovedagainsttheelectricfield,itwillgain:
(a)P.E. (b)K.E (c)mechanicalenergy (d)electricP.E.
Q2.WriteShortanswerstoanysix(6)questions. (2×6=12)
(i).Defineabsoluteelectricpotentialandpotentialgradient.
(ii).StateGauss'slaw.Writedownitsmathematicalexpression.
(iii).ProvethatCoulomb'slawobeythirdlawofmotion.
(iv).Electriclinesofforcenevercross.Why?
(v).Onwhichfactorsdoeselectricfluxdependupon?
(vi).ShowthatN/C=V/m.
(vii).Howcanyouidentifythatwhichplateofacapacitorispositivelycharged?
Note:AttemptanyOne(1)longquestions. (6+4=10)
Q3.(a)Whatiselectricfieldintensity?ApplyGauss'slawtofindelectricfieldintensitybetweentwo
oppositelychargedparallelplates.
(b)Determinetheelectricfieldatthepositionr=(4î+3ĵ)m causedbyapointcharge
q=5.0×10⁻⁶Cplacedatorigin.
Q4.(a)Defineelectricpotential.Derivetheexpressionforelectricpotentialatacertainpointdue
toapointcharge.
(b)Findtheelectricfieldstrengthrequiredtoholdsuspendedaparticleofmass1.0×10⁻⁶kgand
charge1.0μCbetweentwoplates10.0cmapart.
