Assignment title: AC/DC
Learning aim: Examine AC and DC production and health and safety aspects in domestic and
industrial applications
Electrical Safety Awareness
Section 1 AC and DC current
1) Explain the differences and similarities of the properties of AC and DC current in simple circuits
Ans.: AC (alternating current) and DC (direct current) are two types of electrical currents that differ
in the way the electric charge flows through a circuit.
Here are the key differences and similarities between AC and DC in simple circuits:
In direct current, the voltage is always constant, and the electricity flows in a certain direction. In
contrast, in alternating current, the voltage periodically changes from positive to negative and from
negative to positive, and the direction of the current also periodically changes accordingly.
1. Direction of Current Flow:
DC (Direct Current): Electrons flow in one direction only, from the negative terminal to the
positive terminal of the power source.
AC (Alternating Current): Electrons constantly change direction, periodically reversing their
flow. The current alternates between positive and negative cycles.
, 2. Voltage Polarity:
DC: Voltage remains constant in magnitude and polarity. The positive terminal is always at
a higher potential than the negative terminal.
AC: Voltage changes both in magnitude and polarity over time. It oscillates between
positive and negative values.
3. Frequency:
DC: There is no frequency associated with DC. It is a constant, unchanging flow of electrons.
AC: AC has a frequency, which is the number of cycles per second (measured in Hertz).
Common frequencies for household electricity are 50 or 60 Hz.
4. Circuit Components:
DC: Often used in electronic devices, batteries, and most low-voltage applications.
AC: Commonly used in household electrical systems and power distribution grids.
5. Energy Transmission:
DC: Suitable for short-distance power transmission due to higher energy losses over long
distances.
AC: More efficient for long-distance power transmission, as it allows for the use of
transformers to adjust voltage levels.
6. Power Factor:
DC: Power factor is always 1 (unity) since there is no phase difference between voltage and
current.
AC: Power factor may deviate from 1 due to phase differences between voltage and current.
Similarities:
Both AC and DC involve the flow of electric charge in a closed circuit.
Ohm's Law (V = I * R) applies to both AC and DC circuits.
The basic circuit components (resistors, capacitors, inductors) can be used in both AC and DC
circuits.
In summary, while both AC and DC involve the flow of electric current, their key differences lie in the
direction of current flow, voltage characteristics, frequency, and suitability for different applications.
AC is commonly used for power distribution, while DC is often employed in electronic devices and
batteries.
Learning aim: Examine AC and DC production and health and safety aspects in domestic and
industrial applications
Electrical Safety Awareness
Section 1 AC and DC current
1) Explain the differences and similarities of the properties of AC and DC current in simple circuits
Ans.: AC (alternating current) and DC (direct current) are two types of electrical currents that differ
in the way the electric charge flows through a circuit.
Here are the key differences and similarities between AC and DC in simple circuits:
In direct current, the voltage is always constant, and the electricity flows in a certain direction. In
contrast, in alternating current, the voltage periodically changes from positive to negative and from
negative to positive, and the direction of the current also periodically changes accordingly.
1. Direction of Current Flow:
DC (Direct Current): Electrons flow in one direction only, from the negative terminal to the
positive terminal of the power source.
AC (Alternating Current): Electrons constantly change direction, periodically reversing their
flow. The current alternates between positive and negative cycles.
, 2. Voltage Polarity:
DC: Voltage remains constant in magnitude and polarity. The positive terminal is always at
a higher potential than the negative terminal.
AC: Voltage changes both in magnitude and polarity over time. It oscillates between
positive and negative values.
3. Frequency:
DC: There is no frequency associated with DC. It is a constant, unchanging flow of electrons.
AC: AC has a frequency, which is the number of cycles per second (measured in Hertz).
Common frequencies for household electricity are 50 or 60 Hz.
4. Circuit Components:
DC: Often used in electronic devices, batteries, and most low-voltage applications.
AC: Commonly used in household electrical systems and power distribution grids.
5. Energy Transmission:
DC: Suitable for short-distance power transmission due to higher energy losses over long
distances.
AC: More efficient for long-distance power transmission, as it allows for the use of
transformers to adjust voltage levels.
6. Power Factor:
DC: Power factor is always 1 (unity) since there is no phase difference between voltage and
current.
AC: Power factor may deviate from 1 due to phase differences between voltage and current.
Similarities:
Both AC and DC involve the flow of electric charge in a closed circuit.
Ohm's Law (V = I * R) applies to both AC and DC circuits.
The basic circuit components (resistors, capacitors, inductors) can be used in both AC and DC
circuits.
In summary, while both AC and DC involve the flow of electric current, their key differences lie in the
direction of current flow, voltage characteristics, frequency, and suitability for different applications.
AC is commonly used for power distribution, while DC is often employed in electronic devices and
batteries.
