PHY102: Electricity, Magnetism & Modern Physics TMA3

Question 1 : ______________________ forces, hold electrons to nuclei, atoms and molecules together to give rise to bulk matter
A.electrostatic
B.electrolite
C.electromotive
D.electric

Answer to Question 1 is A.electrostatic

 

Question 2 : A ______________________ is the amount of charge that flow through a cross-section of a wire in one second if there is a steady current of one ampere (I A) in the wire
A.coulomb
B.potential
C.Hooke’s
D.electric charge

Answer to Question 2 is D. electric charge

Question 3 : There are _____________ types of elctric charges
A.four
B.three
C.two
D.one

Answer to Question 3 is C. two

Question 4 : Two ebonite rods rubbed with fur and suspended from a rigid support close to each other by threads will ____________________ each other
A.relax
B.contract
C.attract
D.repel

Answer to Question 4 is D. repel

Question 5 : A voltmeter connected across a 60Hz ac source reads 240V. Write down the expression of the instanteneous voltage as a function of time.
A.240cos339.4t
B.240sin339.4t
C.339.4sin377t
D.377cos339.4t

Answer to Question 5 is C.339.4sin377t

 

Question 6 : The work function of a metal is 3.45eV. Calculate th maximum wavelength of a photon that can eject photelectrons from the metal
A.3.6×10−7m
B.3.4×10−7m
C.2.4×10−8m
D.1.6×10−6m

Answer to Question 6 is A.3.6×10−7m

 

Question 7 : The half-life of a certain radioactive isotope is 32 hours. What fraction of the sample would remain after 16 huors?
A.0.25
B.0.71
C.0.62
D.0.50

Answer to Question 7 is B. 0.71

 

Question 8 : A potentiometer wire of length 100cm has a resistance of 10Ω. It is connected in series to to a resistance R and a cell of emf 2V and negligible internal resistance. A source of emf of 10mV is balanced by a length of 40cm of the potentiometer wire. What is the value of the resistance R?
A.2000Ω
B.950Ω
C.200Ω
D.790Ω

Answer to Question 8 is D.790Ω

 

Question 9 : A spectral line is emitted when an atom undergoes transition between two levels with a difference in energy of 2.4eV. What is the wavelength of the line?
A.287nm
B.377angstrome units
C.518nm
D.507angstrome units

Answer to Question 9 is C. 518nm

 

Question 10 : The law of _____________________ of charge states that the total electric charge in an isolated system, that is, the algebraic sum of the positive and negative charge present at any time, does not change
A.moment
B.energy
C.conservation
D.momentum

Answer to Question 10 is C. conservation

 

Question 11 : An RLC circiut contains an ac voltage source with rms value of 50V and has a frequency of 600Hz. Suppose that a resistance R = 20 Ω, capacitance C = 10.0 μF and an inductance L = 4.0mH are connected in series to the source. Find the current in the circuit and the voltmeter reading across the inductor.
A.0.13A and 12.1V
B.4.0A and 23.1V
C.2.17A and 32.8V
D.1.6A and 24.2V

Answer to Question 11 is C.2.17A and 32.8V
Question 12 : The electric field due to a distribution of charges, according to the _________________________ principle, is the vector sum of the fields of the individual charges making up the distribution
A.permeability
B.permittivity
C.superposition
D.distributive

Answer to Question 12 is C. superposition

 

Question 13 : An air-cored transformer is assumed to be 100% efficient. The ratio of the secondary turns to the primary turns is 1:20. A 240V ac supply is connected to the primary coil and a 6Ω load is connected to the secondary coil. what is the current in the primary coil?
A.40.0A
B.2.0A
C.0.14A
D.0.10A

Answer to Question 13 is A. 40.0A

 

Question 14 : When a copper surface is illuminated by radiation of wavelength 2537 angstrome units the value of the stopping potential is found to be 0.24volts. Calculate the work function of copper.
A.7.46eV
B.3.26eV
C.2.67eV
D.4.48eV

Answer to Question 14 is D. 4.48eV

 

Question 15 : An RLC circuit is used to tune a radio set to receive NOUN RADIO broadcasting at 105.9MHz in the FM band. The resistance and the inductance of the circuit of the radio set are 12Ω and 1.4μH respectively. What capacitance should the circuit have?
A.1.64pF
B.1.33mF
C.2.11pF
D.1.51μF

Answer to Question 15 is A. 1.64pF

 

Question 16 : In the relation k=14πϵo, ϵo is the ___________________ of free space
A.permeability
B.permittivity
C.momentum
D.Coulomb

Answer to Question 16. B. permittivity

 

Question 17 : The force exerted by charged particles on each other when they are at rest in a frame of reference is called __________________ force
A.electromotive
B.electrostatic
C.electrolite
D.electric

Answer to Question 17 is B. electrostatic

 

Question 18 : An ac circuit consists of a voltage source v=200sin120πt and a 6μF capacitor in series. Calculate the current established in the circuit
A.0.32A
B.0.64A
C.2.13A
D.1.24A

Answer to Question 18 is A. 0.32A

 

Question 19 : Objects with net unlike charges ____________________ each other
A.attract
B.repel
C.contract
D.relax

Answer to Question 19 is B. repel

 

Question 20 : If Q1 and Q2 are the magnitude of two charges and r the distance between them, ________________’s law states that the electric force exerted by one charge on the other F is F=kQ1Q2r2, where k is a constant
A.electric charge
B.Hooke’s
C.potential
D.Coulomb

Answer to Question 20 is D. coulomb