13 Circuits - 4th Form

Question 1

Why are the bulbs dimmer in the second circuit?

Answer 1

Voltage is shared between bulbs in series

Less voltage across each bulb therefore bulb is dimmer.

Question 2

Define voltage

Answer 2

Energy per unit charge either supplied by a cell, or transferred to a component.

Question 3

What component symbol is shown below?

Answer 3

Light dependent resistor

Question 4

What is voltage measured in?

Answer 4

Volts or V

Question 5

What is the voltage across a cell or power supply a measure of?

Answer 5

The energy transferred from chemical store electrically to the wires per coulomb

Question 6

What component symbol is shown below?

Answer 6

bulb

Question 7

What component symbol is shown below?

Answer 7

ammeter

Question 8

Define current

Answer 8

• The rate of flow of charge

OR

• the number of coulombs passing a point in a circuit per unit time

(It is not the speed of the electrons!)

Question 9

What happens to the total resistance and current in a circuit as more bulbs are added in parallel

Answer 9

Adding bulbs in parallel decreases the total resistance

V=IR

I = V / R

as resistance decreases, current increases for the same voltage

Question 10

How will the current change if the resistance of a circuit is decreased for the same voltage?

Answer 10

current will increase

Question 11

To investigate how the currect varies with voltage in a filament bulb, fixed resistor and diode you should use the cirucit below.

Why does the circuit need a variable resistor?

Answer 11

To vary the voltage across the component

Independent variable is voltage

Dependent variable is current

Question 12

What is resistance?

Answer 12

• The tendency of a material to resist the flow of an electrical current.
• A measure of how much voltage is needed per amp of current.

Question 13

How does the resistance vary with light intensity on a LDR?

Answer 13

As light intensity increases, resistance decreases

Question 14

What is a volt?

Answer 14

1 V = 1 J/C

1 volt = 1 joule per coulomb

Question 15

How does voltage related to current and resistance?

Answer 15

V=IR

Question 16

What is true about the current in a series circuit?

Answer 16

Current is the same everywhere in a series circuit

Question 17

What type of circuit is this? Series or parallel?

Answer 17

Series circuit

Only one path or branch in the circuit

Question 18

What are the prongs of a plug made of brass but the wires made of copper?

Answer 18

Brass is strong and will not bend

Copper is a good conductor of electricity and ductile (can be drawn into wires)

Question 19

What component symbol is shown below?

Answer 19

thermistor

Question 20

How does voltage across bulbs in a series and parallel circuit differ?

Answer 20

Current is conserved in all circuits

Series - current is the same everywhere in the circuit

Parallel - current splits between the branches- current into a junction equals current out of a junction

Question 21

What is the unit for current?

Answer 21

ampere / amps or A

Question 22

What component symbol is shown below?

Answer 22

buzzer

Question 23

What component symbol is shown below?

Answer 23

voltmeter

Question 24

What component symbol is shown below?

Answer 24

Fuse

Question 25

What component symbol is shown below?

Answer 25

Light emitting diode

Question 26

What component symbol is shown below?

Answer 26

motor

Question 27

Bulbs in series provide a larger resistance than bulbs in parallel With this in mind, which circuit draws a larger current from the cell?

Answer 27

V = IR I = V / R as resistance decreases, the current increases for the same voltage The second circuit draws a larger current from the cell, bulbs are in parallel and the total resistance is smaller than the first circuit (series circuit)

Question 28

Each cell provides 3 V. In which circuit (series or parallel are the bulbs brighter?

Answer 28

**Bulbs in parallel are brighter = both have 3V across them (brighter)** Bulbs in series have 1.5 v across each (dimmer) Series- voltage is shared - V_Cell = V₁ + V₂ Parallel - each bulb gets the full voltage of the cell - V_cell = V₁ = V₂

Question 29

How does current differ between series and parallel circuits?

Answer 29

Current is conserved in all circuits Series - current is the same everywhere in the circuit Parallel - current splits between the branches- current into a junction equals current out of a junction

Question 30

How does the resistance of an LDR vary with light intensity?

Answer 30

As light intensity increases, resistance decreases

Question 31

Describe what it means when 1 A is passing through a circuit

Answer 31

1 A = 1 Coulomb per second

Question 32

The IV graph below is for an ohmic conductor... Give an example of an ohmic conductor.

Answer 32

1. fixed resistor 2. wire (if at constant temperature)

Question 33

Below is the IV graph for a....

Answer 33

filament bulb

Question 34

Explain why the second circuit draws a lower current from the cell?

Answer 34

circuit with two bulbs in series - has larger resistance V=IR I = V/R as resistance increases, current decreases for same voltage

Question 35

What component symbol is shown below?

Answer 35

diode

Question 36

For a wire - as temperature increases, resistance also increases. The graph below shows the opposite. What component is this graph for?

Answer 36

Thermistor

Question 37

What component symbol is shown below?

Answer 37

variable resistor

Question 38

What component symbols are shown below?

Answer 38

battery/two cells & solar cell