Energy and Voltage in circuits

Question 1

What is parallel circuits best for?

Answer 1

For domestic lighting (turning a light of in a room), household electrics

Question 2

What is series circuits best for?

Answer 2

Fairy lights

Question 3

How would you calculate current in a series circuit?

Answer 3

Current = voltage/resistance
I = V/R

Question 4

Unit for current

Answer 4

Ampere (A)

Question 5

Unit for electrical charge

Answer 5

Coulomb (C)

Question 6

Unit for energy

Answer 6

Joules (J)

Question 7

Unit for resistance

Answer 7

Ohms (Ω)

Question 8

Unit for time

Answer 8

Seconds (s)

Question 9

Unit for voltage

Answer 9

Volts (V)

Question 10

Unit of power

Answer 10

Watt (W)

Question 11

What happens if a circuit is broken or a component is removed in a series circuit?

Answer 11

It will all stop working

Question 12

Does the current change in a series circuit?

Answer 12

No it stays the same everywhere

Question 13

What does the size of current depend on in a series circuit?

Answer 13

The size of current depends on the potential difference (v)

Question 14

How is the potential difference (v) shared in a series circuit?

Answer 14

It’s shared between components and the p.d. depends on the resistance of the component

Question 15

How to calculate total resistance? (Rtotal)

Answer 15

Total resistance = resistance1 + resistance 2…
Rtotal = R1 +R2…

Question 16

What does the total resistance in a circuit depend on?

Answer 16

The number and type of components.

Question 17

How is the current shared in parallel circuits?

Answer 17

The current is shared between branches

Question 18

How to calculate total current?

Answer 18

Add up the separate currents of each component.
ITotal = I1 +I2

Question 19

What happens if you remove or disconnect a component in a parallel circuit?

Answer 19

It will hardly effect the other components

Question 20

How is the voltage shared in a parallel circuit?

Answer 20

The voltage is the same throughout

Question 21

How does the current change in a branch depending on the components?

Answer 21

The current depends on the resistance, high resistance of component = lower current flow

Question 22

How does the total resistance change if a second resistor is added in a parallel?

Answer 22

The total resistance will decrease. It will be less than the smaller resistor

Question 23

What does the current equal going in a branch and going out the same branch?

Answer 23

They will equal the same as current is conserved.

Question 24

How to calculate charge (Q)?

Answer 24

Charge = Current x Time
Q = I X t

Question 25

What is potential difference (voltage)?

Answer 25

Is energy per unit charge dissipated across an external component

Question 26

What is EMF?

Answer 26

Electric Motor Force - energy per unit charge supplied by the source

Question 27

How to calculate energy transferred using charge and voltage?

Answer 27

Energy transferred = Charge x Voltage E = Q x V

Question 28

How to calculate energy transferred using charge, current and resistance?

Answer 28

Energy transferred = charge x current x resistance E = Q x I x R

Question 29

How does current and voltage vary in wires?

Answer 29

Current is proportional to voltage (at a constant temperature). Straight line

Question 30

How does current and voltage vary in different resistors?

Answer 30

Current is proportional to voltage (at a constant temperature). Different resistors have different resistances so it will have different slopes. Straight line

Question 31

How to calculate the gradient of a resistor (axis's current and voltage)?

Answer 31

The gradiant = 1/resistance

Question 32

How does current and voltage vary in metal filament lamps?

Answer 32

Voltage increases as current does, increased current means increased temperature of filament. This causes the resistance of the filament to increase. This causes a curve

Question 33

How does current and voltage vary in diodes?

Answer 33

Current only flows in one direction (positive). Vt is 0.6v

Question 34

What is Vt?

Answer 34

Threshold voltage - the voltage at which the current flows in a diode.

Question 35

How can you tell if the current is running in a circuit using components?

Answer 35

An LED or lamp can indicate the presence of current

Question 36

How would you get the graphs for wire, metal filament lamp, diode and resistors?

Answer 36

You apply this to a standard test circuit (using a variable resistor, your component, an Ammeter and voltmeter)

Question 37

What is an LDR and what does it look like on a graph?

Answer 37

Light-depending-resistor - In a bright light it has a low resistance and in dim light it has a high resistance. Has a curved line

Question 38

What are LDR's used for?

Answer 38

Useful for night lights

Question 39

What is a thermistor and what does it look like on a graph?

Answer 39

When hot resistance is low, when cold resistance is high.

Question 40

What are thermistors used in?

Answer 40

Useful in thermostats

Question 41

What is current?

Answer 41

It's the rate of flow of charge

Question 42

What is the electrical current in solid metal conductors?

Answer 42

It's the flow of negatively charged electrons

Question 43

What is a volt (using joule and coulomb)?

Answer 43

It's a joule per coulomb