Topic 2 - Electricity

Question 1

what is a current

Answer 1

A current is a flow of electrical charge

Question 2

What is potential difference

Answer 2

potential difference (voltage) is the driving force that pushes the charge around. V

Question 3

What happens if the resistance is greater

Answer 3

the greater the resistance across the component, the smaller the current that flows.

Question 4

Electric current flow equation

Answer 4

Q = IT
Q = charge of flow (Coulombs, C)
I = current (A) 
T = time (S)

Question 5

resistance equation

Answer 5

V = IR
V = potential difference (V)
I = Current (A)
R = Resistance (Ω)

Question 6

Resistance characteristics

Answer 6

Ohmic resistors have a constant resistance

the resistance doesn’t change with the current.

Question 7

I-V characteristics (Lamp, ohmic, Diode)

Answer 7

ohmic conductor - linear
Filament lamp - rounded ‘S’ shape
Diode - starts flat then exponentially rises

Question 8

What happens to the resistance of a resistor of a filament lamp and diode

Answer 8

it changes throughout the components due to it being not linear.

Question 9

what are some circuit devices

Answer 9

LDR - dependant on light, lighter = less resistance, darker = more resistance.
Thermistor - Temp dependant, hotter = less resistance colder = more resistance

Question 10

what are series circuits (resistance, current, potential difference)

Answer 10

-Circuits are connected end to end.
-the potential difference is shared between the
components
-the current is the same everywhere in the circuit
-the total resistance is the sum of two components

Question 11

How to work out the Potential difference, resistance, and current in a series circuit.

Answer 11

V(total) = V(1) + V(2) + ... 
I(1) = I(2) = ...
R(total) = R(1) + R(2)

Question 12

what are parallel circuits (resistors, current, PD)

Answer 12

• parallel circuits are independent and isolated
• The potential difference across the circuit is the same
• The current is shared between the circuit.
• adding more resistors to a circuit reduces the resistance

Question 13

How to work out the potential difference and current in a parallel circuit

Answer 13

V(1) = V(2) = ...
I(total) = I(1) + I(2) + ...

Question 14

What are the two types of electrical supplies

Answer 14

Alternating current (ac) and direct current (dc)

Question 15

properties of an ac supply and a dc supply

Answer 15

the current is constantly changing direction

alternating currents are produced by alternating voltages where the ends keep alternating between positive and negative