Electrical Basic Concept MCQs
1) The diameter of an atom is about:
- 10-10 m
- 10-02 m
- 10-08 m
- 10-15 m
2) 1 cm3 of copper at room temperature has about:
- 200 free electrons
- 20×1010 free electrons
- 8.5×1022 free electrons
- 3×1028 free electrons
3) The mass of a proton is ……………… the mass of electron.
- equal to
- less than
- about 625 times
- 200 times
4) If the number of valence electrons of an atom is 4, then the substance is usually a
- conductor
- insulator
- semiconductor
- none of the above
5) The electrons in the last orbit of an atom are called
- free electrons
- bound electrons
- valence electrons
- thermionic electrons
6) One coulomb of charge is equal to the charge on
- 625×1016 electrons
- 6.25×1016 electrons
- 62.5×1016 electrons
- 0.625×1016 electrons
7) The electric current is due to the flow of
- positive charges only
- negative charges only
- both positive and negative charges
- neutral particles only
8) E.M.F in a circuit
- increases circuit resistance
- decreases circuit resistance
- maintains potential difference
- none of the above
9) Potential difference has the unit of
- charge
- energy
- power
- none
10) The electric current in a liquid is due to the flow of
- electrons only
- protons only
- negative and positive ions
- electrons and positive ions
11) The electric current in a discharge tube containing a gas is due to
- electrons only
- positive ions only
- positive and negative ions
- electrons and positive ions
12) Electric current is a
- scalar quantity
- vector quantity
- number only
- none of the above
13) A billion electrons passes through a cross section of a conductor in 10-3 seconds. The current is
- 1.6×10-7 A
- 2×10-7 A
- 10-7 A
- 2.6×10-7 A
14) How long does it takes 50μC of charge to pass a point in a circuit if the current flow is 15 mA
- 3.33×10-3 seconds
- 6×10 seconds
- 2 seconds
- none of the above
15) The specific resistance of a wire depends upon its
- length
- cross sectional area
- dimension
- material