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Electronics Physics Quiz | objective questions | Physics General Knowledge Questions | MCQ

1 >>which of the following methods can be used to charge a metal sphere positively without touching it . Select the best ?
  • (A) Rub it with a piece of fur
  • (B) Rub it with a piece of silk
  • (C) Bring a negatively charged rod near the sphere and touch it to ground for a short while
  • (D) Connect the positive terminal a battery and float the other end of the battery
2 >>If 109 electrons move out of a body to another body every second, how much time is approximately required to get a total charge of 1 C on the other body? ?
  • (A) 180 years
  • (B) 220 years
  • (C) 200 years
  • (D) 120 years
3 >>Electric charge ?
  • (A) is a property of neutrons onlz
  • (B) is a property of electrons only
  • (C) is a property of protons only
  • (D) is a property of particles such as atoms,ions,electrons etc that defines their behaviour in electrical fields.
4 >>Electric charges are of ?
  • (A) 4 types
  • (B) 2 types
  • (C) 3 types
  • (D) 5 types
5 >>Conservation of charges in tribo electric charging ?
  • (A) implies half are positively charged and other half are neutral
  • (B) implies both are positively charged
  • (C) implies one is positively charged and the other is negatively charged.
  • (D) implies both are negatively charged
6 >>Two positive charges ?
  • (A) attract each other
  • (B) repel each other
  • (C) always attract each other
  • (D) attract each other at times and repel at other times








7 >>Charge is quantized means ?
  • (A) charges can take on discrete values that are multiples of charge on electron
  • (B) charges can take on discrete values that are multiples of charge on neutron
  • (C) charges can take on any continuous value
  • (D) charges can take on any discontinuous value
8 >>Ionization of a neutral atom is the ?
  • (A) only gain of one or more electrons
  • (B) only gain of one or more neutrons
  • (C) only gain of one or more protons
  • (D) gain or loss of one or more electrons
9 >>electrostatic force is ?
  • (A) force exerted by an electron on a neutron
  • (B) force exerted by one charge on another when the two are moving in a given frame of reference
  • (C) force exerted by one charge on another when the two are at rest in a given frame of reference
  • (D) force exerted by one charge on another when the two are accelerating in a given frame of reference
10 >>Conductors are materials ?
  • (A) that allow movement of electrons
  • (B) that allow only random movement of electrons
  • (C) that allow movement of neutrons
  • (D) that allow movement of protons
11 >>In charging by Induction ?
  • (A) a metallic object is charged by rubbing it with fur
  • (B) a metallic object by touching touching with a charged object
  • (C) a metallic object is charged by bringing a charged object near it
  • (D) a metallic object is charged by rubbing it with silk





12 >>For charges q1 and q2  separated by a distance R the magnitude of the electrostatic force is given by ?
  • (A) F= q1/(4 /pie Eo R2)
  • (B) B . F= q1 q2/(4 /pie Eo R)
  • (C) F= q1 q2/(4 /pie Eo R2)
  • (D) F= q1 q2/(4 /pie Eo R3)
13 >>The unit of charge is ?
  • (A) ohm
  • (B) ampere
  • (C) couloumb
  • (D) volt
14 >>Electric field at a point is defined as ?
  • (A) electric force experienced by two charges at that point
  • (B) electric force per unit charge experienced by a unit charge at that point
  • (C) electric force experienced by a dipole at that point
  • (D) electric force experienced by a charge at that point
15 >>According to superposition of electric fields ?
  • (A) The electric field of any combination of charges is the vector sum of the individual charges.
  • (B) The electric field of any combination of charges is the scalar sum of the fields caused by the individual charges.
  • (C) The electric field of any combination of charges is the vector sum of the fields caused by the individual charges.
  • (D) The electric field of any combination of charges is the cross product of the individual fields.
16 >>Electric field lines can be said to be ?
  • (A) drawing lines of electric fields
  • (B) drawing lines of electric fields
  • (C) lines of equal Electric field
  • (D) graphical representation of electric fields.
17 >>At any point on S on an electric field line ?
  • (A) the perpendicular to the line is in the direction of E⃗ at that point
  • (B) the curvature is in the direction of E⃗  at that point
  • (C) the binormal to the line is in the direction of E⃗ at that point
  • (D) the tangent to the line is in the direction of E⃗  at that point
18 >>An electric dipole is ?
  • (A) a pair of electric charges of equal magnitude q separated by a distance d
  • (B) a pair of electric charges of equal magnitude q but negative sign, separated by a distance d
  • (C) a pair of electric charges of equal magnitude q but opposite sign, separated by a distance
  • (D) a pair of electric charges of equal magnitude q but positive sign, separated by a distance d









19 >>The direction of an electric dipole ?
  • (A) is from negative to positive charge
  • (B) is perpendicular to line from negative to positive charge
  • (C) is perpendicular to line from positive to negative charge
  • (D) is from positive to negative charge
20 >>Electric flux ?
  • (A) Is a measure of the area of electric field through a surface
  • (B) Is a measure of the electric field potential through a surface
  • (C) Is a measure of the electric power through a surface
  • (D) Is a measure of the flow (in analogy with flow of fluids) of electric field through a surface.

21 >>Gauss's law states that ?
  • (A) the total electric field flux coming out of a closed surface equals the net charge enclosed within the volume divided by ε0
  • (B) the total electric field flux coming out of a closed surface equals the charge enclosed within the volume divided by ε0
  • (C) the total electric field flux coming out of a closed surface equals the net charge enclosed within the volume
  • (D) the total electric field flux coming out of an open surface equals the net charge enclosed within the volume divided by ε0
22 >>An electric dipole in an electric field experiences a torque τ ?
  • (A) equal to the scalar product of p⃗   and E
  • (B) equal to the vector product of E⃗  and p
  • (C) equal to the scalar product of E⃗  and p
  • (D) equal to the vector product of p⃗    and E
23 >>For a thin infinitely long straight wire of uniform linear charge density λ at a distance R from the wire The magnitude of E⃗  is ?
  • (A) E=λ/3πϵ0R
  • (B) E==(λ/2πϵ0R). Cosθ
  • (C) E=λ2/2πϵ0R
  • (D) B . E=λ/4πϵ0R
24 >>For an Infinite thin plane sheet of uniform surface charge density σ The magnitude of E⃗  is ?
  • (A) E=σ/2ϵ0
  • (B) E=σ/2ϵ03
  • (C) E=σ2/2ϵ0

  • (D) E=σ/ϵ0







  • 25 >>For a thin spherical shell of uniform surface charge density σ , The magnitude of E⃗  just outside is ?
    • (A) E=4πR2σ/4πϵ0r2
    • (B) E=4πR2σ/4πϵ0r3
    • (C) E=4πRσ2/4πϵ0r2
    • (D) E=R2σ/4πϵ0r2
    26 >>An electric field can deflect ?
    • (A) γ - rays
    • (B) X rays
    • (C) Neutrons
    • (D) α – rays
    27 >>A conducting sphere of radius 5 cm is charged to 15 μ C. Another uncharged sphere of radius 10 cm is allowed to touch it for enough time. After the two are separated, the surface density of charge on the two spheres will be in the ratio ?
    • (A) 0.0423611111111111
    • (B) 0.125694444444444
    • (C) 0.0430555555555556
    • (D) 0.0840277777777778
    28 >>A Gaussian sphere encloses an electric dipole within it. Total flux across the sphere is ?
    • (A) double that due to single charge
    • (B) Zero
    • (C) dependent on position of the charge
    • (D) half that due to a single charge
    29 >>A cylinder of radius R and length L is placed in an uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by ?
    • (A) πR2+πL2
    • (B) 2πR2E
    • (C) 0
    • (D) πR2E
    30 >>A hollow spherical conductor of radius 2m carries a charge of 500 μ C. Then electric field strength at its surface is ?
    • (A) Zero
    • (B) 4.5×106N/C
    • (C) 1.125×106N/C
    • (D) 2.25×106N/C
    31 >>When a negatively charged conductor is connected to earth, ?
    • (A) Electrons flow from the earth to the conductor
    • (B) Electrons flow from the conductor to the earth
    • (C) Protons flow from the conductor to the earth
    • (D) No charge flow occurs.
    32 >>Which of the following cannot be deflected by an electric field ?
    • (A) γ - rays
    • (B) X rays
    • (C) α – rays
    • (D) Both (a) and (b)
    33 >>A tennis ball which has been covered with charges is suspended by a thread so that it hangs between two metal plates. One plate is earthed, while other is attracted to a high voltage generator. The ball ?
    • (A) swings backward & forward hitting each plate in turn
    • (B) is repelled by earthed plate and stays there.
    • (C) hangs without moving
    • (D) is attracted to the high voltage plate and stays there
    34 >>A metallic solid sphere is placed in a uniform electric field. In the figure, which path will the lines of force follow? ?
    • (A) straight
    • (B) curved
    • (C) directed toward center
    • (D) None of these
    35 >>Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be ?
    • (A) Zero
    • (B) 16e/ϵo
    • (C) A .8e/ϵo
    • (D) e/ϵo
    36 >>A charge q is placed at the center of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to ?
    • (A) Q/2
    • (B) Q/3
    • (C) Q/5
    • (D) Q/4
    37 >>Four point charges qA=2μC,qB=−5μC,qC=2μC,andqD=−5μC are located at the corners of a square ABCD of side 10 cm. Force on a charge of 1μC placed at the centre of the square is ?
    • (A) 3.6
    • (B) 4.5
    • (C) 1.8
    • (D) 0
    38 >>A system has two charges qA=2.5×10−7C and qB=−2.5×10−7C located at points A: (0, 0, –15 cm) and B: (0,0, +15 cm), respectively. What are the total charge and electric dipole moment of the system? ?
    • (A) zero, 7.5×10−8Cm
    • (B) zero, 8.5×10−8Cm
    • (C) zero, 6.5×10−8Cm
    • (D) zero, 5.5×10−8Cm
    39 >>An electric dipole with dipole moment 4×10−9C m is aligned at 30 with the direction of a uniform electric field of magnitude 5×104NC−1. Calculate the magnitude of the torque acting on the dipole. ?
    • (A) 1.5×10−8Nm
    • (B) 2.5×10−4Cm
    • (C) 1.0×10−4Cm
    • (D) 3.5×10−4Cm
    40 >>Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is 6.5×10−7C? The radii of A and B are negligible compared to the distance of separation. ?
    • (A) 2.5×10−2N
    • (B) 1.5×10−2N
    • (C) 4.5×10−2N
    • (D) 3.5×10−2N


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