Direct and Alternating Current

Question 1

Q1: What are the two types of electric current?
A: The two types of electric current are direct current (dc) and alternating current (ac). An electric current flows either as a direct current or as an alternating current.

Q2: What is direct current (DC)?
A: Direct current (dc) is an electric current that flows in only one direction. It is a current that is always flowing in the same direction and does not reverse.

Q3: How is direct current produced?
A: Direct current is created by a direct voltage, meaning the voltage does not change direction and remains constant.

Q4: What devices commonly provide direct current?
A: Direct current is provided by cells, batteries (including car batteries and dry cells), and solar cells. It is usually found in battery-powered devices.

Q5: How does direct current appear on a voltage-time graph?
A: On a voltage-time graph, direct current appears as a straight horizontal line at a constant voltage, showing that the voltage does not change over time.

Q6: What is alternating current (AC)?
A: Alternating current (ac) is an electric current that regularly changes direction, switching between positive and negative directions periodically.

Q7: How is alternating current produced?
A: Alternating current is produced by alternating voltages in which the positive and negative ends keep switching. Power stations generate electricity using magnets, which produces an alternating current.

Q8: How does alternating current appear on a voltage-time graph?
A: On a voltage-time graph, alternating current appears as a wave-like curve that alternates between positive and negative voltages. The positive and negative values indicate the direction of current flow.

Q9: What do the positive and negative values on an AC graph represent?
A: The positive and negative values represent the direction of current flow, showing that the current is constantly reversing direction.

Q10: What is the UK mains electricity supply?
A: The UK mains electricity supply is the electrical supply found in homes, shops, offices, and factories, and it is an example of alternating current (ac).

Q11: What is the voltage of the UK mains supply?
A: The UK mains supply is delivered at approximately 230 volts (V).

Q12: What is the frequency of the UK mains supply?
A: The frequency of the UK mains supply is 50 hertz (Hz), which means the current changes direction 50 times per second (50 cycles per second).

Q13: What does frequency mean in the context of alternating current?
A: Frequency refers to how many complete cycles of current occur each second. In the UK mains supply, a frequency of 50 Hz means 50 cycles per second.

Q14: How does alternating current compare to direct current?
A: Alternating current changes direction continuously due to alternating voltages, whereas direct current flows in only one direction and is produced by a constant direct voltage.

Q15: What is the difference between battery supply and mains supply?
A: Battery supply provides direct current (dc), which flows in one direction, whereas mains supply provides alternating current (ac), which constantly changes direction.

Answer 1

Source 1: Direct and Alternating Current:
DIRECT CURRENT (DC) is electrical current flowing in ONE direction.
Direct current is usually found in BATTERY POWERED devices.

ALTERNATING CURRENT (AC) is current that changes direction from positive to negative periodically.
An example of AC is the UK MAINS SUPPLY (Current from sockets in the home). //////////// Source 2: Alternating and direct current:
An electric current flows either as a direct current or as an alternating current.

Direct current:
A direct current flows in only one direction. On a voltage-time graph this would appear as a straight horizontal line at a constant voltage. Car batteries, dry cells and solar cells all provide a direct current (dc) that only flows in one direction.

Alternating Current:
An alternating current regularly changes direction. On a voltage-time graph, this would appear as a curve alternating between positive and negative voltages. The positive and negative values indicate the direction of current flow. Power stations produce electricity using magnets. This provides an alternating current (ac). In the UK, the mains electrical supply (the electrical supply found in homes, shops, offices and factories) is generated at a frequency of 50 Hertz (Hz) and is delivered to houses at 230 Volts (V). //////////// Source 3: Mains Supply is ac, Battery Supply is dc:
1) There are two types of electricity supplies - alternating current (ac) and direct current (dc).
2) In ac supplies the current is constantly changing direction. Alternating currents are produced by alternating voltages in which the positive and negative ends keep alternating.
3) The UK mains supply (the electricity in your home) is an ac supply at around 230 V.
4) The frequency of the ac mains supply is 50 cycles per second or 50 Hz (hertz).
5) By contrast, cells and batteries supply direct current (dc).
6) Direct current is a current that is always flowing in the same direction. It’s created by a direct voltage.

Question 2

Q1: What are the two types of electric current?

Question 3

A: The two types of electric current are direct current (dc) and alternating current (ac). An electric current flows either as a direct current or as an alternating current.

Question 4

Q2: What is direct current (DC)?

Question 5

A: Direct current (dc) is an electric current that flows in only one direction. It is a current that is always flowing in the same direction and does not reverse.

Question 6

Q3: How is direct current produced?

Question 7

A: Direct current is created by a direct voltage

Answer 7

meaning the voltage does not change direction and remains constant.

Question 8

Q4: What devices commonly provide direct current?

Question 9

A: Direct current is provided by cells

Answer 9

batteries (including car batteries and dry cells)

Question 10

Q5: How does direct current appear on a voltage-time graph?

Question 11

A: On a voltage-time graph

Answer 11

direct current appears as a straight horizontal line at a constant voltage

Question 12

Q6: What is alternating current (AC)?

Question 13

A: Alternating current (ac) is an electric current that regularly changes direction

Answer 13

switching between positive and negative directions periodically.

Question 14

Q7: How is alternating current produced?

Question 15

A: Alternating current is produced by alternating voltages in which the positive and negative ends keep switching. Power stations generate electricity using magnets

Answer 15

which produces an alternating current.

Question 16

Q8: How does alternating current appear on a voltage-time graph?

Question 17

A: On a voltage-time graph

Answer 17

alternating current appears as a wave-like curve that alternates between positive and negative voltages. The positive and negative values indicate the direction of current flow.

Question 18

Q9: What do the positive and negative values on an AC graph represent?

Question 19

A: The positive and negative values represent the direction of current flow

Answer 19

showing that the current is constantly reversing direction.

Question 20

Q10: What is the UK mains electricity supply?

Question 21

A: The UK mains electricity supply is the electrical supply found in homes

Answer 21

shops

Question 22

Q11: What is the voltage of the UK mains supply?

Question 23

A: The UK mains supply is delivered at approximately 230 volts (V).

Question 24

Q12: What is the frequency of the UK mains supply?

Question 25

A: The frequency of the UK mains supply is 50 hertz (Hz)

Answer 25

which means the current changes direction 50 times per second (50 cycles per second).

Question 26

Q13: What does frequency mean in the context of alternating current?

Question 27

A: Frequency refers to how many complete cycles of current occur each second. In the UK mains supply

Answer 27

a frequency of 50 Hz means 50 cycles per second.

Question 28

Q14: How does alternating current compare to direct current?

Question 29

A: Alternating current changes direction continuously due to alternating voltages

Answer 29

whereas direct current flows in only one direction and is produced by a constant direct voltage.

Question 30

Q15: What is the difference between battery supply and mains supply?

Question 31

A: Battery supply provides direct current (dc)

Answer 31

which flows in one direction