Circuits

What does this symbolise?

Cell

What does this symbolise?

Battery

What does this symbolise?

Open switch

What does this symbolise?

Closed switch

What does this symbolise?

Bulb/lamp

What does this symbolise?

Fuse

What does this symbolise?

LED

What does this symbolise?

DC power supply

What does this symbolise?

AC power supply

What does this symbolise?

Resistor

What does this symbolise?

Variable resistor

What does this symbolise?

Ammeter

What does this symbolise?

Voltmeter

What does this symbolise?

Diode

What does this symbolise?

LDR

What does this symbolise?

Thermistor

What does this symbolise?

Motor

What is current?

Flow of electrical charge

What is current measured in?

Amperes

What is potential difference?

Driving force that pushes the charge

What unit is potential difference measured in?

Voltage

What is resistance?

Anything that slows the current down

What is resistance measured in?

Ohms

In metals, what is current caused by?

Flow of electrons

What is charge measured in?

Coulombs

What is the symbol for amperes?

I

What is energy measured in?

Joules

What is the symbol for voltage?

V

What happens to resistance (usually) when temperature increases?

Increases

When resistance increases, what happens to current?

Decreases

How does resistance work?

Current has to do work against it and therefore slows down

What does the work done against resistance cause?

Transfer of energy of which some is useful and some is dissapated

When a current flows through a resistor, what happens to its temperature?

Heats up

Why does the resistor heat up when current flows through it?

Electrons collide with the ions and then the ions gain energy, vibrate, heat up, and makes it harder for the electrons to get through the resistor

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

Decreases

What kind of graph is this?

Resistor

What kind of graph is this?

Filament lamp

What kind of graph is this?

Diode

What kind of graph is this?

LDR

What kind of graph is this?

Thermistor

What does LDR depend on?

Light

What happens to LDR resistance in bright light?

Low

What happens to LDR resistance in darkness?

High

What are LDR’s used for?

• Automatic night lights

• Outdoor lighting

• Burglar detectors

What is thermistor dependent on?

Temperature

What happens to thermistor resistance if the temperature is cool?

High

What happens to thermistor resistance if the temperature is hot?

Low

What are thermistors used for?

• Thermostats

• Car engine temperature sensors

What is a series ciruit?

Current flows through one pathway

What is a parallel circuit?

Current flows through more than one pathway

What happens to a series circuit if you remove one component?

It will stop working

What happens to a parallel circuit if you remove one component?

Won’t affect the others at all

How are voltmeters always connect to a circuit - no matter what?

Parallel

What happens to current in a parallel circuit?

It is distributed across components

What happens in a junction of a parallel circuit?

Current splits or rejoins

Does the total current entering a junction equal total current leaving?

Yes

What happens in a series circuit when a resistor is added?

Total resistance increases

What happens in a parallel circuit when a resistor is added?

Total resistance decreases

The larger the current the ____ energy transferred:

a. More

b. Less

More

What happens to efficiency usually when a component is heated?

Reduced

Can components in a circuit melt?

Yes