Physics Multiple Choice Questions on “Electric Currents in Conductors”.
1. Identify the type of materials which develop electric currents in them, when an electric field is applied.
a) Elastomers
b) Conductors
c) Insulators
d) Polymers
Answer: b
Clarification: When an electric field is applied across the ends of conductors, the electrons begin to move under the action of the electric field. The flow of electrons constitutes electric current through the conductor.
2. Which of the following is the most conductive element?
a) Aluminium
b) Lead
c) Silver
d) Hydrogen
Answer: c
Clarification: Silver is one of the most electrically conductive element. This is because electrons can move more freely in silver than any other elements. Silver also has the lowest contact resistance of any metal.
3. In nature, free charged particles exist in the upper strata of the environment called the stratosphere. State true or false.
a) True
b) False
Answer: b
Clarification: Free charged particles exist in the upper strata of environment called the ionosphere. It is a region which is ionized by solar radiation and includes parts of thermosphere, mesosphere and exosphere.
4. To maintain a steady current through the conductor, some external device must do work. What does the external device provide?
a) Inductance
b) Capacitance
c) Potential difference
d) Electromotive force
Answer: d
Clarification: To maintain steady current through the conductor, electromotive force must be provided by the external device to take positive charge from lower potential to higher potential i.e. in the direction opposite to that of the electric field.
5. Identify the type of conductors in which both positive and negative charges can move.
a) Thermosets
b) Metallic conductors
c) Electrolytic solutions
d) Polymers
Answer: c
Clarification: Electrolytic solutions are those that are capable of conducting an electrical current. They are generally ions, in which both positive and negative charges can move. Polymers and thermosets do not conduct electric charge. Electrons are the charge carriers in metallic conductors.