P6 - Electric circuits

Question 1

What are the two types of circuits

Answer 1

series and parallel

Question 2

In a series circuit the current is all the

Answer 2

same at all points within the circuit

Question 3

The current in a circuit can be measured with an

Answer 3

ammeter

Question 4

Voltage across a component can be measured using a

Answer 4

voltmeter

Question 5

In a parallel circuit the current

Answer 5

splits between the two branches of the circuit meaning that the current from the source is larger than the current in a branch

Question 6

In a parallel circuit the current from the source is the sum of the

Answer 6

currents in the separate branches of the circuit

A1 = A2 + A3

Question 7

In a series circuit with 2 resistors the combined resistance is

Answer 7

the sum of the 2 resistors

R1 + R2 = RC

Question 8

In a parallel circuit the combined resistance is

Answer 8

less than the value of either of the two resistors because there are more paths for the charge to pass along

Question 9

When resistors R1 and R2 are in a parallel circuit RC is

Answer 9

RC = (R1 X R2)/(R1 + R2)

Question 10

In series circuit the p.d across the battery equals

Answer 10

the sum of the p.d across each lamp

Question 11

A battery is made by joining

Answer 11

cells together

Question 12

the total e.m.f of three cells would be

Answer 12

E = E1 + E2 + E3

The sum of the individual e.m.f of the cell

Question 13

In series circuits resistors oppose

Answer 13

the flow of electric current through the circuit.

Question 14

total e.m.f of all energy sources =

Answer 14

total p.d across components

Question 15

What are the advantages of connecting a lamp to a parallel circuit over a series circuit

Answer 15

1. Each lamp can be switched on and off separately in a parallel circuit but in a series circuit they all switch off
2. If one lamp breaks current still flows through the other ones in a parallel circuit but in a series circuit if the lamp breaks the whole circuit stops.

Question 16

An input transducer is a circuit that turns a variable outside of the circuit such as temperature or light

Answer 16

into an electrical signal

Question 17

Thermistors and light dependent resistors (LDR)s can be used to make

Answer 17

input transducers.

Question 18

A thermistor is a component whos resistance changes with its

Answer 18

temperature

Question 19

Increasing temperature in a thermistor

Answer 19

decreases resistance

Question 20

A light dependent resistor (LDR) resistance changes

Answer 20

with light intensity

Question 21

Increasing light intensity in a LDR

Answer 21

decreases resistance

Question 22

The change in resistance of an LDR or thermistor changes the

Answer 22

p.d across the resistor

Question 23

A transducer is a device that transfers

Answer 23

energy from one form to another

Question 24

What are some dangers of electricity

Answer 24

Damaged insulation: can get electric shock
Overheating of cables: can cause a fire
damp conditions: water conduct electricity

Question 25

Fuses and circuit breakers protect us from electrical appliances by stopping the

Answer 25

flow of electric current flow if it gets too high stopping overheating

Question 26

Circuit breakers help

Answer 26

switch off the flow of current if too high

Question 27

Fuses contain thin wires that melt if

Answer 27

current is too high in appliance and breaks the circuit

Question 28

What are fuse ratings

Answer 28

tells the level where a fuse will begin to melt

Question 29

The fuse chosen should have a value

Answer 29

just above the normal current of an appliance

Question 30

If an operating current is 3.9 A what is a suitable fuse value 3A 5A or 15A

Answer 30

5A since its just above the normal 3.9A

Question 31

Explain why is a 13 A fuse wrong to use for an appliance with a 3.9 A operating current

Answer 31

More than three times the normal operating current is needed to melt the fuse.
Therefore, the 13 A fuse might not melt even if the appliance developed a fault.