What happens to the impedance in a purely capacitive AC circuit as the frequency increases?
A It increases
B It decreases
C It remains constant
D It becomes zero
In a **purely capacitive AC circuit**, **capacitive reactance (XC)** decreases as the frequency increases, because **XC = 1 / (2πfC)**.
What is the phase shift between the current and voltage in a purely resistive AC circuit?
A 90 degrees
B 0 degrees
C 180 degrees
D 45 degrees
In a **purely resistive AC circuit**, the **current and voltage are in phase**, meaning they reach their maximum and minimum values at the same time, resulting in a **0-degree phase shift**.
What is the cutoff frequency in an electrical filter?
A The frequency at which the filter begins to attenuate the signal
B The frequency at which the impedance is zero
C The maximum frequency the filter can pass
D The frequency at which power is minimized
The **cutoff frequency** is the point at which a filter begins to reduce or block certain frequencies, depending on the type of filter.
What does power factor correction do to improve the efficiency of an electrical system?
A It minimizes the impedance of the circuit
B It aligns the phase between voltage and current
C It stores excess power in capacitors
D It increases the supply voltage
**Power factor correction** reduces the phase difference between current and voltage, making the system more efficient by ensuring more real power is used for work.
What is the main function of transistors in electrical circuits?
A To store energy
B To amplify or switch electronic signals
C To regulate power supply
D To control the frequency of signals
**Transistors** are used to amplify signals or act as switches, enabling them to control the flow of current in various types of circuits.
What happens when a capacitor is placed in series with a resistor in an AC circuit?
A The current becomes zero
B The capacitor blocks DC while allowing AC to pass
C The capacitor stores all the energy
D The voltage across the resistor and capacitor is equal
When a capacitor is placed in series with a resistor in an AC circuit, it allows **AC signals** to pass through while blocking **DC signals** after the capacitor is fully charged.
In a parallel circuit, what happens when resistors are added?
A The total resistance decreases
B The total resistance increases
C The total voltage decreases
D The current becomes zero
In a **parallel circuit**, adding more resistors provides additional paths for current to flow, which reduces the total resistance of the circuit.
What is the primary purpose of diodes in circuits?
A To store electrical energy
B To allow current to flow in only one direction
C To resist current flow
D To amplify signals
**Diodes** are semiconductor devices that allow current to flow in only one direction, which makes them essential in rectifying circuits, converting AC to DC.
How does resonance affect the impedance in a series RLC circuit?
A It increases the impedance
B It decreases the impedance to a minimum value
C It causes the current to be zero
D It increases the voltage
At **resonance** in a series **RLC circuit**, the **inductive reactance (XL)** and **capacitive reactance (XC)** cancel each other out, resulting in the minimum impedance and maximum current.
What does an inductor store in an AC circuit?
A Energy in the form of an electric field
B Energy in the form of a magnetic field
C Energy in the form of a resistive element
D Energy in the form of a capacitive element
An **inductor** stores energy in the form of a **magnetic field** when current flows through it. This stored energy can be released when the current changes.
What does **Ohm’s Law** state?
A Voltage is inversely proportional to current
B Voltage is equal to current times resistance
C Power is equal to current times resistance
D Resistance is equal to current times voltage
**Ohm’s Law** states that the voltage (V) across a resistor is directly proportional to the current (I) flowing through it and the constant of proportionality is the resistance (R). The formula is **V = I * R**.
What does **Kirchhoff’s Current Law (KCL)** state?
A The sum of the current entering a junction equals the sum of the current leaving the junction
B The sum of the voltages in a loop equals zero
C The current in a parallel circuit is constant
D The total power in a circuit is constant
**Kirchhoff’s Current Law (KCL)** states that the total current entering a junction (node) is equal to the total current leaving that junction, based on the principle of conservation of electric charge.
What does **Kirchhoff’s Voltage Law (KVL)** state?
A The sum of currents entering a junction equals the sum of currents leaving the junction
B The sum of the voltages in a closed loop equals zero
C The power supplied equals the power consumed
D The total resistance in a circuit is constant
**Kirchhoff’s Voltage Law (KVL)** states that the sum of all voltages around a closed loop in a circuit must equal zero, based on the principle of conservation of energy.
What happens to the current in a **series circuit** as more resistors are added?
A The current increases
B The current decreases
C The current stays the same
D The total resistance decreases
In a **series circuit**, adding more resistors increases the total resistance, which causes the current to decrease, according to **Ohm’s Law** (**I = V / R**).
How do you calculate the total resistance in a **parallel circuit**?
A R_total = R1 + R2 + … + Rn
B 1/R_total = 1/R1 + 1/R2 + … + 1/Rn
C R_total = R1 * R2 * … * Rn
D R_total = (R1 + R2) / 2
In a **parallel circuit**, the total resistance is calculated by taking the reciprocal sum of the reciprocals of the individual resistances: **1/R_total = 1/R1 + 1/R2 + … + 1/Rn**.
What happens to the voltage in a **parallel circuit**?
A It is divided among the components
B It is the same across all components
C It is zero across all components
D It increases with the number of components
In a **parallel circuit**, the voltage across each component is the same as the source voltage.
What is **impedance** in an AC circuit?
A The total resistance to current flow, including reactance
B The total power consumed
C The total capacitance in the circuit
D The energy stored in inductive components
**Impedance** is the total opposition to current flow in an AC circuit, which includes both **resistance** (R) and **reactance** (X).
What is the purpose of a **transformer** in an AC circuit?
A To step up or step down voltage levels
B To regulate the current
C To convert AC to DC
D To amplify signals
A **transformer** is used to either **step-up** or **step-down** voltage levels in an AC circuit, enabling efficient transmission of electricity over long distances.
What is the phase difference between current and voltage in a **purely inductive** AC circuit?
A 90 degrees (current lags voltage)
B 0 degrees
C 45 degrees
D 180 degrees
In a **purely inductive** AC circuit, the **current lags the voltage by 90 degrees** because inductors resist changes in current flow.
What happens at **resonance** in an RLC circuit?
A The inductive and capacitive reactances cancel each other out
B The total current decreases
C The impedance increases
D The current becomes zero
At **resonance** in an RLC circuit, the **inductive reactance (XL)** and **capacitive reactance (XC)** cancel each other out, resulting in the minimum impedance and maximum current.
What is the **phase shift** between current and voltage in a purely resistive AC circuit?
A 0 degrees
B 90 degrees (current lags voltage)
C 180 degrees
D 45 degrees
In a **purely resistive** AC circuit, the **voltage and current are in phase**, meaning their waveforms reach their maximum and minimum values at the same time, with a **0-degree phase shift**.
What is the role of **capacitors** in an AC circuit?
A To store energy in the form of a magnetic field
B To store energy in the form of an electric field
C To resist changes in current
D To amplify signals
**Capacitors** store electrical energy in the form of an **electric field** between their plates and can release it when needed. They are used for filtering and smoothing signals.
What is the **current** behavior in an AC circuit when the impedance increases?
A The current decreases
B The current increases
C The voltage increases
D The current stays constant
As the **impedance** increases in an AC circuit, the **current decreases** because impedance is the opposition to current flow, and a higher impedance results in less current for the same applied voltage.
What is the primary purpose of **digital circuits**?
A To process signals in discrete binary values (0 and 1)
B To process signals in continuous values
C To store energy
D To control the current in a circuit
**Digital circuits** process signals represented by discrete binary values, typically **0 and 1**, and are widely used in computing, logic gates, and other digital systems.
What happens when **resistors** are added to a **series circuit**?
A The total resistance increases
B The total resistance decreases
C The current increases
D The voltage remains constant
In a **series circuit**, adding more resistors increases the **total resistance**, which decreases the current based on **Ohm’s Law**.
What happens to the **total resistance** in a **parallel circuit** when resistors are added?
A The total resistance increases
B The total resistance decreases
C The total resistance remains the same
D The total current decreases
In a **parallel circuit**, adding more resistors decreases the total resistance because additional paths are created for the current to flow through, reducing the overall opposition.
What is the **cutoff frequency** in an electrical filter?
A The frequency at which the filter starts to attenuate the signal
B The frequency at which the impedance is zero
C The frequency at which the filter allows the maximum signal
D The frequency at which the voltage is minimized
The **cutoff frequency** is the point at which the filter starts to reduce or attenuate the signal, above or below which the filter significantly weakens the signal.
What happens when the **impedance** in an AC circuit increases?
A The current decreases
B The current increases
C The voltage increases
D The power decreases
In an AC circuit, **impedance** is the opposition to current flow. If the impedance increases, the **current decreases**, assuming the voltage remains constant (Ohm’s Law: I = V / Z).
What happens to the **current** in a **parallel circuit** when more resistors are added?
A The current increases
B The current decreases
C The voltage increases
D The total resistance increases
In a **parallel circuit**, when more resistors are added, additional paths for current are created, so the **total current increases** while the total resistance decreases.
What is the **primary role of resistors** in electrical circuits?
A To limit the flow of current
B To store electrical energy
C To convert electrical energy into mechanical energy
D To increase the voltage across components
**Resistors** are used to limit the flow of current in a circuit, preventing damage to other components and controlling the amount of energy delivered to them.
What is Ohm’s Law?
A Voltage equals current divided by resistance
B Voltage equals current times resistance
C Resistance equals voltage times current
D Power equals voltage times current
**Ohm’s Law** states that the voltage across a resistor is equal to the current flowing through it multiplied by the resistance. The formula is **V = I * R**.
What does Kirchhoff’s Current Law (KCL) state?
A The sum of the currents in a closed loop equals zero
B The sum of the currents entering a junction equals the sum of the currents leaving the junction
C The total voltage in a series circuit is the sum of individual voltages
D The voltage across any two points in a circuit is constant
**Kirchhoff’s Current Law (KCL)** states that the sum of currents entering a junction is equal to the sum of currents leaving that junction, based on the conservation of charge.
What does Kirchhoff’s Voltage Law (KVL) state?
A The sum of currents entering a junction is equal to the sum leaving the junction
B The sum of the voltages in a closed loop equals zero
C The total resistance in a series circuit equals the sum of individual resistances
D The voltage drop across a component is constant in a parallel circuit
**Kirchhoff’s Voltage Law (KVL)** states that the sum of all voltages around a closed loop in a circuit must equal zero, based on the conservation of energy.
What is the characteristic of a series circuit?
A The voltage across all components is the same
B The total current is the same throughout the circuit
C The total current is divided among the components
D The total resistance decreases with more components
In a **series circuit**, the current is the same throughout all components, while the voltage divides among the components according to their resistances.
How do you calculate the total resistance in a parallel circuit?
A R_total = R1 + R2 + … + Rn
B 1/R_total = 1/R1 + 1/R2 + … + 1/Rn
C R_total = R1 * R2 * … * Rn
D R_total = (R1 + R2) / 2
In a **parallel circuit**, the total resistance is calculated by taking the reciprocal of the sum of the reciprocals of the individual resistances:
**1/R_total = 1/R1 + 1/R2 + … + 1/Rn**.
What happens to the impedance in a purely inductive AC circuit as the frequency increases?
A The impedance decreases
B The impedance increases
C The impedance stays constant
D The impedance becomes zero
In a **purely inductive AC circuit**, **inductive reactance (XL)** increases with frequency. The formula for **XL** is **XL = 2πfL**, where **f** is the frequency and **L** is the inductance.
What is the resonance condition in an RLC circuit?
A The impedance is maximized
B The inductive reactance equals the capacitive reactance
C The total current is minimized
D The voltage across the circuit is minimized
**Resonance** in an **RLC circuit** occurs when the **inductive reactance** (**XL**) equals the **capacitive reactance** (**XC**). This results in minimal total impedance and maximized current.
What is the **total power** in a resistive AC circuit?
A P = V * I * cos(θ)
B P = I² * R
C P = V² / R
D P = V * I
In a **resistive AC circuit**, the power dissipated is calculated as **P = I² * R**, where **I** is the current and **R** is the resistance.
What happens to the **impedance** in a purely capacitive AC circuit as the frequency increases?
A The impedance increases
B The impedance decreases
C The impedance stays the same
D The impedance becomes zero
In a **purely capacitive AC circuit**, the **capacitive reactance (XC)** decreases as the frequency increases because **XC = 1 / (2πfC)**.
What happens to the **total resistance** in a series circuit when additional resistors are added?
A The total resistance decreases
B The total resistance increases
C The total resistance stays the same
D The total current decreases
In a **series circuit**, adding resistors increases the total resistance because the resistances are added together.
What happens to the **voltage** in a **parallel circuit**?
A The voltage is divided among the components
B The voltage is the same across all components
C The voltage is zero across each component
D The voltage increases with the number of components
In a **parallel circuit**, the voltage across each component is the same as the supply voltage, regardless of the number of components.
What is **resonance** in an RLC circuit?
A The impedance is maximized
B The inductive reactance equals the capacitive reactance
C The total current is minimized
D The voltage is minimized
**Resonance** occurs when the **inductive reactance (XL)** equals the **capacitive reactance (XC)**, which results in maximum current flow and minimum impedance.
What happens to the **total current** in a parallel circuit when more resistors are added?
A The current decreases
B The current increases
C The current remains the same
D The current becomes zero
In a **parallel circuit**, adding more resistors provides additional paths for the current to flow, which increases the total current supplied by the source.
What is **impedance** in an AC circuit?
A The total resistance only
B The total resistance to current flow, including reactance
C The energy stored in the circuit
D The power consumed by the circuit
**Impedance** is the total opposition to current flow in an AC circuit, combining both **resistance (R)** and **reactance (X)**. It is measured in ohms (Ω).
What happens to the **voltage** in a series circuit if the total resistance increases?
A The voltage across each resistor remains the same
B The voltage across each resistor increases
C The total voltage decreases
D The current becomes zero
In a **series circuit**, when the total resistance increases, the voltage across each resistor increases proportionally according to **Ohm’s Law**, with **V = I * R**.
What happens in a purely resistive AC circuit if the frequency increases?
A The resistance increases
B The impedance stays the same
C The current increases
D The impedance decreases
In a **purely resistive AC circuit**, the **impedance** remains constant regardless of the frequency, since **impedance** is only dependent on **resistance** in such circuits.
What is the **phase difference** between current and voltage in a purely capacitive AC circuit?
A Current leads voltage by 90 degrees
B Voltage leads current by 90 degrees
C Voltage and current are in phase
D There is no phase difference
In a **purely capacitive AC circuit**, the **voltage leads the current by 90 degrees**, meaning the voltage reaches its peak one-quarter cycle before the current.
What is the unit of **inductance** in an AC circuit?
A Volt
B Ampere
C Henry
D Ohm
The unit of **inductance** is the **henry (H)**. Inductance measures the ability of an inductor to resist changes in current and is an important factor in determining the impedance of inductive components.
What is the **total power** in an AC circuit with a **power factor of 1**?
A The total power is less than the apparent power
B The total power is equal to the real power
C The total power is zero
D The total power is equal to the apparent power
When the **power factor** is **1**, all of the **apparent power** is converted into **real power**, meaning the circuit is operating at maximum efficiency with no reactive power losses.
What does **energy transfer** in an electrical circuit refer to?
A The movement of energy from the source to the load
B The movement of electrical energy from the source to the load
C The dissipation of power as heat
D The conversion of electrical energy to light
**Energy transfer** refers to the movement of electrical energy from the **source** (like a power supply) to the **load** (such as a light bulb or motor), where it is consumed or stored.