Current electricity

Question 1

Insulating

Answer 1

Reducing energy transfer by conduction

Question 2

Electron

Answer 2

A tiny particle with a negative charge

Question 3

Attract

Answer 3

To cause to move nearer

Question 4

Repel

Answer 4

To cause to move apart

Question 5

Series

Answer 5

Components connected in a circuit so that the same current passes through them

Question 6

Potential difference

Answer 6

The amount of work done by each coulomb of charge that passes through a component

Question 7

Parallel

Answer 7

Components connected in a circuit so that the potential difference is the same across each one

Question 8

Volt (V)

Answer 8

The unit of potential difference

Question 9

V=W/Q=E/Q

Answer 9

potential difference (V) = work done (J) ÷ charge (C) = energy transferred (J) ÷ charge (C)

Question 10

Resistance

Answer 10

The opposition to current flow, measured in ohms, Ω

Question 11

R=V/I

Answer 11

resistance (Ω) = potential difference (V) ÷ current (A)

Question 12

Ohmic conductor

Answer 12

A conductor that has a constant resistance, and therefore obeys Ohm’s law

Question 13

I=Q/t

Answer 13

current (A) = charge (C) ÷ time

Question 14

Filament bulb

Answer 14

An electrical device designed to produce light

Question 15

Diode

Answer 15

An electrical device that allows current through in one direction only

Question 16

Light-dependent resistor (LDR)

Answer 16

A device with a resistance that varies with the amount of light falling on it

Question 17

Thermistor

Answer 17

A device with a resistance that varies with temperature

Question 18

What happens when insulating materials are rubbed together?

Answer 18

Certain insulating materials become charged when rubbed together

Question 19

What is transferred when objects become charged?

Answer 19

Electrons are transferred when objects become charged

Question 20

What happens when charges are brought together?

Answer 20

Like charges repel; unlike charges attract

Question 21

Why are electric charges represented by circuit diagrams?

Answer 21

Every component has its own agreed symbol. A circuit diagram shows how components are connected together

Question 22

What is the difference between a battery and a cell?

Answer 22

A battery consists of two or more cells connected together

Question 23

What determines the size of an electric current?

Answer 23

The size of an electric current is the rate of flow of charge

Question 24

What do we mean by potential difference?

Answer 24

The potential difference is the amount of work done by each coulomb of charge that passes through a component

Question 25

What is Ohm's law?

Answer 25

Ohm's law states that the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor

Question 26

What happens if you reverse the current in a resistor?

Answer 26

Reversing the current through a component reverses the pd across it

Question 27

What happens to the resistance of a filament bulb as its temperature increases?

Answer 27

The resistance increases with the increase of the filament temperature

Question 28

Why does the resistance of a filament bulb increase as its temperature increases?

Answer 28

The ions in the metal filament vibrate more as the temperature, so they resist the passage of electrons through the filament more

Question 29

How does the current through a diode depend on the potential difference across it?

Answer 29

In the "forward" direction a diode's resistance is low; in the "reverse direction" the resistance is high

Question 30

What happens to the resistance of a thermistor as its temperature increases?

Answer 30

The resistance decreases if the temperature increases

Question 31

What happens to the resistance of an LDR as the light level increases?

Answer 31

The resistance decreases if the light intensity on it increases

Question 32

What can we say about the current and potential difference for components in a series circuit?

Answer 32

For components in series, the current is the same in each component, and adding the potential differences gives the total potential difference

Question 33

How can we find the total resistance of resistors in series?

Answer 33

Adding the resistances gives the total resistance of resistors in series

Question 34

What can we say about the potential difference of several cells in series?

Answer 34

For cells in series, acting in the same direction, the total potential difference is the sum of their individual potential differences

Question 35

What can we say about the currents in the components of a parallel circuit?

Answer 35

For components in parallel, the total current is the sum of the currents through the separate components, and the bigger the resistance of a component, the smaller its current is

Question 36

What can we say about the potential differences across the components in a parallel circuit?

Answer 36

In a parallel circuit the potential difference is the same across each component