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SilcoatesScience
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What name is given to current that only flows in one direction?
Direct current (dc)

What sort of current is supplied by cells and batteries?
Direct current (dc)

What do the letters a.c. represent?
Alternating current

What is the period of an ac wave?
 The time for a complete cycle

What is the relationship between the frequency (f) and the time period (T) of an ac wave?
(T in seconds, f in Hz)

What names are given to the three wires in a UK mains plug?

Some mains cables only have two wires. Which wire is missing?
Earth

Which one of the 3 mains wires are circuit breakers and fuses always connected into?
Live

What happens to a fuse if the current exceeds the rating of the fuse?
It melts, thereby breaking the circuit

Which acts the fastest, a fuse or a circuit breaker?
circuit breaker

Which appliances are usually earthed?
 Those with metal cases

What is the purpose of the earth wire?
By providing a lowresistance path for the current to flow in the event of a fault, it enables the fuse to blow and break the circuit

What happens when an electrical charge flows through a resistor?
It gets hot

In a filament lamp, what is most of the electrical energy converted into?
Heat (wasted)

What is the unit of power?
Watt (W)

What is the unit of energy?
Joule (J)

What is the unit of electrical current?
Amperes (Amps) (A)

What is the unit of electrical charge?
Coulomb (C)

What is the relationship between energy (E), potential difference (V) , and charge (Q)
E = V x Q

Are electrons negatively or positively charged?
Negatively

What causes some insulating materials to become electrically charged when they are rubbed together?
Electrons are rubbed off one material and onto the other

What happens when two electrically charged objects (that have the same charge) are brought together?
They repel each other

Give an example of a type of material that electrical charges can move through easily
Metals

What is electric current?
A flow of electric charge

What is the unit of electrical current?
Ampere (Amp) (A)

How is the size of a current (I) calculated from the total charge (Q) and time (t)?
I = Q/t

What is the standard unit of electrical charge?
Coulomb (C)

What is potential difference another name for ?
Voltage

What component is this graph for?
Resistor

What is the unit of resistance?
Ohm

If a component has a larger resistance, will the current be larger or smaller?
Smaller

In a series circuit, what do you know about the current at different points?
It is always the same

In a series circuit how is the total resistance calculated?
By adding up the individual resistances

For components connected in parallel what do you know about the potential difference across each component?
They are all the same

What component is this graph for?
Filament bulb

Which component only allows current to flow one way?
Diode

What component is this graph for?
Diode

What happens to the resistance of an LDR as light intensity increases?
The resistance decreases

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

Which component emits light when a current flows through it in a forward direction?
Light Emitting Diode (LED)

