P2 key questions

State the rule for current in a series circuit the current is the same at every point in the circuit and in every component

State the rule for potential difference in a series circuit the total potential difference of the power supply is shared between components

State the rule for resistance in a series circuit the more resistors, the greater the resistance. RT=R1+R2

State the rule for current in a parallel circuit the total current through the whole circuit is the sum of the currents through the separate components

State the rule for potential difference in a parallel circuit the potential difference across each branch in the circuit is the same

State the rule for resistance in a parallel circuit adding more resistors in parallel decreases resistance

What colour is the live wire in a three core cable? brown

What colour is the neutral wire in a three core cable? blue

What colour is the earth wire in a three core cable? green and yellow

The brown wire in a plug is the _______ live

The blue wire in a plug is the ________ neutral

The green and yellow wire in a plug is the ________ earth

The potential difference between the live wire and others in the plug is _____ V 230V

Current flows into an appliance through the _______ wire live

Current flows out of an appliance through the ______ wire neutral

The _________ wire is a safety feature of appliances earth

Potential difference between the neutral wires and others in the plug should be ____ V 0V

Electric Current is….? the flow of electric charge

Potential difference between two points in a circuit is….? the work done when a couloumb of charge passes between the points.

In a circuit the potential difference causes …..? charge to flow

Resistance is…? caused by anything which opposes the flow of electric charge

Particles which can be 'charges' in electric circuits are… electrons or ions

What is a series circuit? A circuit with only one route for charge to flow

What is a parallel circuit? A circuit with more than one route for charge to flow

State the equation which links charge flow, current and time Q=It

State the equation which links current, potential difference and resistance V=IR

State the equation which links current, potential difference and power P=IV

State the equation which links current, power and resistance P=I2R

State the equation which links energy transferred, power and time E=Pt

State the equation which links charge flow, energy transferred and potential difference E=QV

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

What is the unit of current? Amps (A)

What is the unit for potential difference? Volts (V)

What is the unit for resistance? Ohms (Ω)

What is the unit for power? Watts (W)

Draw the I-V characteristic for a fixed resistor teacher to draw on board…

Draw the I-V characteristic for a filament lamp see teacher to draw on board…

Draw the I-V characteristic for a diode teacher to draw on board…

Describe the I-V characteristic for a fixed resistor Current and potential difference are directly proportional, resistance is constant

Describe the I-V characteristic of a filament lamp Resistance is not constant, it increases as p.d. increases

Explain why resistance increases with increased p.d. in a filament lamp temperature increases causing ions to vibrate and increasing collisions with electrons flowing through the filament

Describe the I-V characteristic of a diode The current only flows through the diode in one direction, there is a very high resistance in the reverse direction.

Current which regularly changes direction is called… alternating current

An example of alternating current is…? mains electricity

Current which flows in one direction is…? direct current

An example of direct current is… batteries

What is the potential difference of mains electricity in the UK? 230V

What is the frequency of the alternating current in UK mains electricity? 50Hz

The national grid consists of…? Cables and transformers

Are power stations par of the national grid? no

What does a step up transformer do? Increases p.d.

What does a step down transformer do? reduces p.d. to 230 V

Why are transformers used? reduce current so that less heat is lost in cables, increases efficiency