Basic Fundamentals

Question 1

What is the formula for total charge that crosses a conductor’s cross-section in time dt?

Answer 1

dg = nAev dt

Where n is the number of free electrons per cubic meter, A is the area of cross-section, e is the charge of each electron, and v is the drift velocity.

Question 2

What is the relationship between current (I) and current density (J)?

Answer 2

I = J·A

This indicates that current is the product of current density and the cross-sectional area.

Question 3

What is the typical drift velocity of electrons in a conductor?

Answer 3

Typically a fraction of a metre per second

Drift velocity is very slow compared to the speed of the electrical field propagation.

Question 4

What is the formula for current density (J)?

Answer 4

J = ne v

Where n is the free electron density, e is the charge of an electron, and v is the drift velocity.

Question 5

What is the magnitude of the current density for a copper conductor given n = 10 and e = 1.6 x 10^-19 C?

Answer 5

1.55 x 10^6 A/m^2

This is calculated based on the given values and the relationship J = n e v.

Question 6

Fill in the blank: The speed with which charge drifts in a conductor is called the _______.

Answer 6

velocity of charge

Question 7

What is the velocity of propagation of the electrical field in a conductor?

Answer 7

Approximately 3 x 10^8 m/s

This velocity is independent of current and voltage.

Question 8

True or False: The electron drift velocity is independent of the current flowing and the area of the conductor.

Answer 8

True

Question 9

What is the Fermi speed in relation to electron movement?

Answer 9

It is the speed at which electrons move, with only a tiny drift velocity superimposed by the applied electric field.

Question 10

Calculate the magnitude of current if the free-electron density is 10^10 electrons/m^3, the cross-sectional area is 1 cm², and the drift velocity is 1.5 x 10^-3 m/s.

Answer 10

0.24 A

Current is calculated using the formula i = nAev.

Question 11

What is the significance of the term ‘current density’?

Answer 11

It is the current per unit area and is denoted by the symbol J.

Question 12

What is Ohm’s Law?

Answer 12

Ohm’s Law states that the current through a conductor between two points is directly proportional to the voltage across the two points.

Question 13

True or False: Voltage is measured in Amperes.

Answer 13

False. Voltage is measured in Volts.

Question 14

Fill in the blank: The unit of electrical resistance is ___.

Answer 14

Ohm

Question 15

What is the formula for calculating power in an electrical circuit?

Answer 15

Power (P) = Voltage (V) x Current (I)

Question 16

What does a capacitor do in a circuit?

Answer 16

A capacitor stores and releases electrical energy.

Question 17

Multiple Choice: Which of the following components can store energy? A) Resistor B) Capacitor C) Inductor

Answer 17

B) Capacitor

Question 18

What is the purpose of a resistor in a circuit?

Answer 18

A resistor limits the flow of electric current.

Question 19

True or False: In a series circuit, the total resistance is the sum of individual resistances.

Answer 19

True

Question 20

Fill in the blank: The total current in a parallel circuit is equal to the ___ of the currents through each path.

Answer 20

sum

Question 21

What is Kirchhoff’s Voltage Law?

Answer 21

Kirchhoff’s Voltage Law states that the sum of the electrical potential differences (voltage) around any closed network is zero.

Question 22

Multiple Choice: In which type of circuit does current remain the same through all components? A) Series B) Parallel

Answer 22

A) Series

Question 23

What is a short circuit?

Answer 23

A short circuit is an unintended path of low resistance that allows current to flow, bypassing the intended load.

Question 24

True or False: The equivalent resistance in a parallel circuit is always less than the smallest individual resistance.

Answer 24

True

Question 25

Fill in the blank: The unit of capacitance is ___.

Answer 25

Farad

Question 26

What are the two main types of current?

Answer 26

Alternating Current (AC) and Direct Current (DC)

Question 27

Multiple Choice: Which law is used to analyze current flow in circuits? A) Ohm's Law B) Faraday's Law C) Newton's Law

Answer 27

A) Ohm's Law

Question 28

What is the function of an inductor in a circuit?

Answer 28

An inductor stores energy in a magnetic field when electric current flows through it.

Question 29

True or False: The total voltage in a series circuit is equal to the sum of the individual voltages across each component.

Answer 29

True

Question 30

Fill in the blank: The symbol for a resistor in a circuit diagram is ___.

Answer 30

a zigzag line

Question 31

What is the effect of increasing resistance in a circuit while keeping voltage constant?

Answer 31

The current will decrease.

Question 32

Multiple Choice: What is the primary purpose of a fuse in a circuit? A) Increase voltage B) Protect against overload C) Store energy

Answer 32

B) Protect against overload

Question 33

What is the relationship between voltage, current, and resistance known as?

Answer 33

Ohm's Law

Question 34

True or False: Capacitors can block DC current while allowing AC current to pass.

Answer 34

True

Question 35

Fill in the blank: The total capacitance in a parallel circuit is equal to the ___ of the capacitances.

Answer 35

sum

Question 36

What is a voltmeter used for?

Answer 36

A voltmeter is used to measure the voltage across two points in a circuit.

Question 37

Multiple Choice: What type of circuit allows multiple paths for current to flow? A) Series B) Parallel

Answer 37

B) Parallel

Question 38

What does DC stand for in DC network theorems?

Answer 38

Direct Current

Question 39

True or False: Ohm's Law states that V = I * R.

Answer 39

True

Question 40

What is the principle of superposition in DC circuits?

Answer 40

The principle that the response in a linear circuit with multiple sources can be found by considering each source independently.

Question 41

Fill in the blank: Thevenin's theorem simplifies a complex circuit to a single __________ and __________.

Answer 41

voltage source, series resistance

Question 42

What is the formula for calculating equivalent resistance in series circuits?

Answer 42

R_eq = R1 + R2 + ... + Rn

Question 43

True or False: Norton's theorem states that any linear circuit can be replaced by an equivalent current source in parallel with a resistance.

Answer 43

True

Question 44

What is the formula for calculating equivalent resistance in parallel circuits?

Answer 44

1/R_eq = 1/R1 + 1/R2 + ... + 1/Rn

Question 45

Define Thevenin equivalent circuit.

Answer 45

A simplified representation of a circuit that consists of a single voltage source in series with a resistance.

Question 46

What does KCL stand for?

Answer 46

Kirchhoff's Current Law

Question 47

What does KVL stand for?

Answer 47

Kirchhoff's Voltage Law

Question 48

True or False: KVL states that the sum of all voltages around a closed loop is equal to zero.

Answer 48

True

Question 49

What is the significance of a short circuit in a DC network?

Answer 49

A short circuit provides a path of low resistance, which can lead to excessive current flow.

Question 50

Fill in the blank: In a series circuit, the total current is __________.

Answer 50

the same through all components

Question 51

What is the main purpose of using mesh analysis in DC circuits?

Answer 51

To find the currents in the circuit by applying KVL in the loops.

Question 52

What is the main purpose of using nodal analysis in DC circuits?

Answer 52

To find the voltages at the nodes in the circuit using KCL.

Question 53

What is the formula for power in a DC circuit?

Answer 53

P = V * I

Question 54

True or False: The total power supplied by sources is equal to the total power consumed by loads in a DC circuit.

Answer 54

True

Question 55

What is the effect of adding resistors in series?

Answer 55

The total resistance increases.

Question 56

What is the effect of adding resistors in parallel?

Answer 56

The total resistance decreases.

Question 57

What is a dependent source in a circuit?

Answer 57

A source whose value depends on another voltage or current in the circuit.

Question 58

Fill in the blank: Thevenin's theorem can be used to analyze __________.

Answer 58

linear circuits

Question 59

What is the primary use of Norton's theorem?

Answer 59

To simplify complex circuits into a current source and parallel resistance.

Question 60

What is the relationship between Thevenin and Norton equivalents?

Answer 60

They are duals; Thevenin's voltage source can be converted to Norton's current source and vice versa.

Question 61

What do you call a circuit that has only resistors and DC sources?

Answer 61

Linear circuit

Question 62

True or False: A voltage divider is used to create a lower voltage from a higher voltage in a DC circuit.

Answer 62

True

Question 63

What is electrical work?

Answer 63

Electrical work is said to be done when an electric charge flows under a potential difference.

Question 64

Define electrical power.

Answer 64

Electrical power is the rate of transfer of electrical energy or the rate of electrical work.

Question 65

What is the capacity to do work in mechanics referred to as?

Answer 65

Energy.

Question 66

What does the skin effect refer to?

Answer 66

The action of alternating current that causes more of a current to flow near the outside surface than in the center of a conductor.

Question 67

Define eddy current.

Answer 67

Eddy current, or Foucault current, means the current induced in the interior of conducting masses by variation of the magnetic flux.

Question 68

What is a unilateral circuit?

Answer 68

A unilateral circuit is an electrical circuit in which the properties or characteristics change with respect to current or voltage.

Question 69

What is a bilateral circuit?

Answer 69

A bilateral circuit is an electrical circuit which has constant properties or characteristics in both directions.

Question 70

What is a nonlinear network?

Answer 70

A nonlinear network means the network of electrical elements in which the parameters are not constant.

Question 71

Fill in the blank: Electrical work is the product of _______ and time.

Answer 71

power

Question 72

True or False: In mechanics, power is defined as the rate of doing energy.

Answer 72

False

Question 73

Fill in the blank: In electrical work, the flow of charge 'Q' occurs under a potential difference '______'.

Answer 73

V

Question 74

Unit of power and electrical energy

Answer 74

Power ----- Watt Electrical Energy---- Watt-hr