Basic electrics

Question 1

Front

Answer 1

Back

Question 2

What is the result of increasing the voltage in a circuit?

Answer 2

More current can flow around the circuit.

Question 3

What is the result of reducing the resistance of a circuit?

Answer 3

More current can flow.

Question 4

A circuit has a resistance of 6Ω and a current flow of 2A. What is the applied voltage?

Answer 4

12V

Question 5

A 24V supply is connected across a 6Ω resistance. How much current is flowing?

Answer 5

4A

Question 6

A circuit has 12V applied and 6A flowing. What is the resistance?

Answer 6

2Ω

Question 7

A 230V supply is connected across a 0.5Ω resistance. How much current will flow?

Answer 7

460A

Question 8

Two points in a circuit are at +24V and +12V with a 6Ω resistance between them. How much current is flowing?

Answer 8

2A (because the potential difference is 12V).

Question 9

A 6Ω component is connected between two points that are both at 230V. How much current will flow?

Answer 9

0A

Question 10

A 12V, 6W lamp is connected to a circuit. How much current will flow?

Answer 10

0.5A

Question 11

A lamp has 6V across it and 4A flowing through it. What is the wattage of the lamp?

Answer 11

24W

Question 12

A circuit has a power of 48W and a current of 12A. What is the supply voltage?

Answer 12

4V

Question 13

A 48W load is connected between 36V and 12V. How much current will flow?

Answer 13

2A (because the potential difference is 24V, so I = P/V = 48/24).

Question 14

A circuit has 12V across a 24Ω resistance. How much power is consumed?

Answer 14

6W

Question 15

A voltmeter is connected across a load that has 12V across it (between 12V and 0V). What will the voltmeter read?

Answer 15

12V

Question 16

A voltmeter is connected across two points that are electrically the same point in a circuit. What will it read?

Answer 16

0V

Question 17

A voltmeter is connected between a point at +12V and a point at 0V. What will it read?

Answer 17

12V

Question 18

An open circuit has +12V on one side and 0V on the other. How much current will flow?

Answer 18

0A

Question 19

A complete circuit has +12V across a 24Ω load. How much current will be flowing?

Answer 19

0.5A

Question 20

In a simple series circuit with a +12V supply and a 24Ω load, what is the total current flow?

Answer 20

0.5A

Question 21

A +24V supply is connected across a 12Ω load with an ammeter in series. What will the ammeter read?

Answer 21

2A

Question 22

A +12V supply is connected across a 12Ω load. What will the ammeter read, and what will the voltmeter read across the load?

Answer 22

Ammeter = 1A; Voltmeter = 12V.

Question 23

In a closed circuit with a +12V supply and a 24Ω load, what will the two ammeters read, and what will the voltmeter read across the load?

Answer 23

Both ammeters = 0.5A; voltmeter = 12V.

Question 24

In an open switch circuit with a +12V supply and a 24Ω load, what will the two ammeters read, and what will the voltmeter read across the open switch?

Answer 24

Both ammeters = 0A; voltmeter = 12V.

Question 25

In an open switch circuit with a +12V supply and a 24Ω load, what will the two ammeters read, and what will the voltmeter read across a section of conductor with no potential difference?

Answer 25

Both ammeters = 0A; voltmeter = 0V.

Question 26

With a +12V supply and 24Ω load, if the circuit remains open and the voltmeter is placed across the load itself, what will the readings be?

Answer 26

Both ammeters = 0A; voltmeter = 0V.

Question 27

With a +12V supply and 24Ω load, if the circuit remains open and the voltmeter is placed across the supply side of the break, what will the readings be?

Answer 27

Both ammeters = 0A; voltmeter = 12V.

Question 28

With a +12V supply and 24Ω load, if the circuit is complete and the voltmeter is placed across a plain conductor, what will the readings be?

Answer 28

Both ammeters = 0.5A; voltmeter = 0V.

Question 29

A +50V supply is connected across a 50Ω load. What will the ammeter read?

Answer 29

1A

Question 30

A +50V supply is connected across a 5Ω load. What will the ammeter read?

Answer 30

10A

Question 31

A +50V supply is connected across a 0.5Ω load. What will the ammeter read?

Answer 31

100A

Question 32

If a short circuit occurs and the circuit resistance is effectively 0Ω, what will the ammeter read?

Answer 32

MAX / extremely high current.

Question 33

How much current will a 10,000W cooker draw when connected to a 230V supply?

Answer 33

43.48A

Question 34

A domestic lighting circuit is protected by a 6A circuit breaker. What is the maximum number of 100W lamps that can be connected to a 230V supply?

Answer 34

13 lamps

Question 35

Express 8.4kW in watts.

Answer 35

8400W

Question 36

Express 100mA in amps.

Answer 36

0.1A

Question 37

Express 0.03A in milliamps.

Answer 37

30mA

Question 38

Express 0.5MΩ in kilo-ohms.

Answer 38

500kΩ

Question 39

At 230V, how many amps are there in 1kW?

Answer 39

4.35A (approximately 4A per kW for quick estimating).

Question 40

In a three-phase system, what is the voltage between any line and neutral?

Answer 40

230V

Question 41

In a three-phase system, what is the voltage between any two lines?

Answer 41

400V

Question 42

In a three-phase system, what is the voltage between neutral and earth?

Answer 42

0V