Electricity Basics - Part Two

Q1: what are the basic electrical circuit elements? 

The three basic circuit elements are resistors, capacitors, and inductors.

Q2: what is the definition of the term “Electrical Resistance”? 

The electrical resistance of a circuit component or device is defined as the ratio of the voltage applied to the electric current which flows through it.



Q3: what is the definition of the term “Resistivity”? 

Resistivity is a Material property which measures how strongly this material opposes the flow of electric current at a given temperature.


Q4: what is the definition of the term “Electrical Conductivity”? 

The electrical conductivity is he inverse of electrical resistivity.


Q5: are the resistivity and conductivity temperature dependent? 

Yes, the resistivity and conductivity are temperature dependent.

Q6: what is a capacitor? 
Capacitor is a charge storage device

Q7: does the capacitor permit passing DC current? Why? 
No, the capacitor didn’t permit passing the DC current.

Reason for this is that capacitor impedance = 1/(2Πfc)

It is known that the F (frequency) of DC current = Zero, so capacitor impedance = 1/Zero = infinity

The capacitor shows large impedance for the DC current, so capacitor will bock passing of DC current.



Q8: what is the definition of the term “Capacitance”? 
The Capacitance is a measure of the amount of electrical energy stored (or separated) for a given electric potential on a capacitor.

Q9: what is the inductor? 
An inductor is a device that tries to keep a constant current flowing through itself.


Q10: what is the definition of the term “Impedance”? 
Impedance is a complex Quantity ( has magnitude and phase angle) characterize the voltage-current relationships in an AC circuit.



Q11: what is the definition of the term “Admittance”? 
The Admittance is the reciprocal of the impedance.

Q12: what is the Equivalent Resistance for a group of resistances connected in series? 
R Equivalent = R1+R2+R3+……

Q13: what is the Equivalent Resistance for a group of resistances connected in Parallel? 
1/R Equivalent = 1/R1+1/R2+1/R3+……

Q14: what is the measuring unit of Resistance? 
Measuring unit of Resistance is ohm (Ω).

Q15: what is the Equivalent Capacitance for a group of Capacitors connected in series? 
1/C Equivalent = 1/C1+1/C2+1/C3+……

Q16: what is the Equivalent Capacitance for a group of Capacitors connected in Parallel? 
C Equivalent = C1+C2+C3+……

Q14: what is the measuring unit of Resistance? 
Measuring unit of Capacitance is Farad (F) and usually expressed in micro unit as (µF).

Basic Electrical Engineering