TMA1/PHY102

My TMA Home TMA Results My Pending TMA Quick Help My TMATMA InstructionCourse DetailTMA CalendarGrading Message BoardQuick InfoInstructor Message Quiz NoteQuiz Tip - 1Quix Tip - 2 TMA Quiz Questions TMA: TMA1/PHY102 Matric Number:  SCORE=10.00 PHY102 - Electricity, Magnetism and Modern Physics Mr. Ibanga Efiong (eibanga@noun.edu.ng ) 1 When amber is rubbed with fur amber is positively charged while fur is negatively charged amber is negatively charged while fur is positively charged amber is positively charged while fur is neutral amber is negatively charged while fur is neutral 2 Two charges Q1=500μC$$Q_1=500\mu C$$ and Q2=100μC$$Q_2=100\mu C$$ are located on the XY plane at the positions r1=3j⃗ $$r_1=3\overrightarrow{j}$$ m and r2=4i⃗ $$r_2=4\overrightarrow{i}$$ m . Find the force exerted on the Q2$$Q_2$$ 14.4i⃗ +10.8j⃗ $$14.4\overrightarrow{i}+10.8\overrightarrow{j}$$ N 14.4i⃗ –10.8j⃗ $$14.4\overrightarrow{i}–10.8\overrightarrow{j}$$ N 10.8i⃗ –14.4j⃗ $$10.8\overrightarrow{i}–14.4\overrightarrow{j}$$ N 10.8i⃗ +14.4j⃗ $$10.8\overrightarrow{i}+14.4\overrightarrow{j}$$ N 3 A huge spark due to electric discharge in the atmosphere produces all of the following except Lightning Rapid expansion of surrounding air shock waves gamma radiation. 4 Which of the following is not true of an electrostatic force? it acts along the line joining the point charges it obeys an inverse square law it is mutually attractive or repulsive  it is weaker than the gravitational attraction between the charged particles. 5 A tiny ball of mass 0.60 g is suspended from a rigid support with a piece of thread in a horizontal electric field of intensity 700 N/C. The ball is in equilibrium when the thread is inclined at an angle of 20o$${20}^o$$ to the vertical. What are the magnitude and sign of the charge on the ball? Take g=9.8m/s2$$g=9.8m/s^2$$ −3.1×10−6C$$-3.1\times {10}^{-6}C$$ 3.2×10−6C$$3.2\times {10}^{-6}C$$ 4.2×10−6C$$4.2\times {10}^{-}6C$$ −4.1×10−3$$-4.1\times {10}^{-3}$$ 6 The following are true about electric field lines except that they  are drawn such that the magnitude of the field is proportional to the number of lines crossing a unit area perpendicular to the lines do not intersect one another are discontinuous and may terminate in a vacuum give the direction of motion of a unit positive test-charge under the action of the electrostatic force 7 What are the dimensions of the constant k in Coulomb’s law of electrostatics? ML2T−4T−2A−1$$M{L}^2{T}^{-4}T-2A^{-1}$$ ML2T3A−2$$M{L}^2{T}^3{A}^{-2}$$ M−2L3T2A−1$$M^{-2}{L}^3{T}^2{A}^{-1}$$ ML3T−4A−2$$M{L}^3{T}^{-4}{A}^{-2}$$ 8 Which of the following can be used to charge a metal rod that is held in your hand? Rub it with fur silk wool It cannot be done 9 Which of the following is a conductor plastic copper glass silk 10 Charges of +2$$+2$$ and −2C$$-2C$$ are situated at points P and Q respectively which are at a distance apart. A point X is mid-way between P and Q. Which of the following correctly describes the electric field and the electric potential at point X? electric field is toward Q, electric potential is zero electric field is toward Q, electric potential is negative electric field is toward P, electric potential zero electric field is toward P, electric potential is positive 11 From Gauss’ law which of the following is NOT correct? The outward flux of electric field through an enclosed surface is proportional to the electric charges enclosed The field at a point outside a spherically symmetric charge is the same as the electric field at the same point due to a point charge at its centre. The electric flux through a Gaussian surface is a vector product of the electric field and a unit vector perpendicular to and outward from the surface The total electric flux through a cylinder placed in an electric field with its axis parallel to the field is zero 12 Which of the following is not true about the electric field intensity E⃗ $$\overrightarrow{E}$$ of a uniformly charged solid sphere? E⃗ $$\overrightarrow{E}$$ is maximum at the surface of the sphere E⃗ $$\overrightarrow{E}$$ is directly proportional to the distance from the centre of the sphere E⃗ $$\overrightarrow{E}$$ decreases as a square of the distance from the surface of the sphere E⃗ $$\overrightarrow{E}$$ decreases as a square of the distance from the centre of the sphere. 13 1 volt is equal to 1 watt/C 1 J/s C 1 J/C 1 N/C 14 The electric potential difference between two points A and B is 42 V. What is the work done by an external agent in carrying a charge of 5.0×10−5C$$5.0\times {10}^{-5}C$$ from A to B at constant speed? 2.1×10−3J$$2.1\times {10}^{-3}J$$ 8.4×10−4J$$8.4\times {10}^{-4}J$$ 21×10−4J$$21\times 10-4J$$ 8.4×10−3J$$8.4\times {10}^{-3}J$$ 15 A uniform electric field of 200 N/C is in the x-direction. A point charge of 3μC$$3\mu C$$ is released from rest at the origin. What is the kinetic energy of the charge when it is at x = 4 m? 2.4×10−2J$$2.4\times {10}^{-2}J$$ 1.6×10−2J$$1.6\times {10}^{-2}J$$ 3.6×10−2J$$3.6\times {10}^{-2}J$$ 4.8×10−2J$$4.8\times {10}^{-2}J$$ 16 The term 'lost volts' refers to ----------- energy per coulomb dissipated in the external (load) resistance terminal potential difference energy per coulomb dissipated in the internal resistance of the source of emf energy per coulomb wasted to heat up the connecting wires 17 Kirchhof's junction rule is statement of conservation of ----------- mass energy charge momentum 18 A galvanometer of resistance 120Ω$$120\mathrm{\Omega }$$ a full scale deflection with a current of 0.0005A. How would you convert it to an ammeter that reads a maximum current of 5A? connect 2000Ω$$2000\mathrm{\Omega }$$ in parallel to it connect 200.12Ω$$200.12\mathrm{\Omega }$$ in series to it connect 20.10Ω$$20.10\mathrm{\Omega }$$ in series to it connect 0.012Ω$$0.012\mathrm{\Omega }$$ in parallel to it 19 Kirchhof's loop rule is statement of conservation of ----------- mass energy charge momentum 20 In the space surrounding a wire carrying a steady current, there exists a magnetic field pointing radially outward a magnetic field circling the wire an oscillating magnatic field no magnatic field