ENERGY+AND+POTENTIAL+DIFFERENCE+IN+CIRCUITS

IGCSE PHYSICS > ELECTRICITY =ENERGY AND POTENTIAL DIFFERENCE IN CIRCUITS=
 * MAINS ELECTRICITY || ENERGY AND PD || ELECTRIC CHARGE ||

Potential difference means voltage
Objectives printed like this are Core Curriculum: papers 1 and 2 media type="custom" key="12909724" [|MEET DR MEGAVOLT] - BBC video interview with a man who has a Tesla Coil!
 * Objectives printed like this are Extended Curriculum: paper 2 only **

**INTRO ACTIVITIES**
NUMBER ONE: TESTING CONDUCTORS WITH A SIMULATION

4 links to PHET website. [|BATTERY VOLTAGE SIMULATION] - this is a good one to play with to see what happens in a battery [|BATTERY RESISTOR CIRCUIT] - this one hows how the electrical energy from the battery is converted to heat in a resistor [|OHM'S LAW] [|AC CIRCUIT CONSTRUCTION KIT] - everything you learn in circuit electricity you can try out here.

LINK TO THE CIRCUIT SYMBOLS YOU NEED TO KNOW FOR IGCSE

NUMBER TWO: **INVESTIGATION OF REAL ELECTRICAL COMPONENTS**

2.9 explain why a series or parallel circuit is more appropriate for particular applications, including domestic lighting

SERIES: Components connected end to end in a chain. PARALLEL: Components connected in a ladder formation.

2.10 understand that the current in a series circuit depends on the applied voltage and the number and nature of other components AMMETER: An instrument which measures electric current. It must be connected in series with the current it is measuring. VOLTMETER: An instrument which measures the potential difference between two points. It must be connected in parallel with the PD it is measuring.

**ELECTRICITY VOCABULARY** measure components in and are connected measure components in and are connected NUMBER THREE: **SERIES AND PARALLEL CIRCUITS ACTIVITY**
 * ** VOLTMETERS **
 * VOLTAGE (PD) **
 * ACROSS **
 * VOLTS **
 * IN PARALLEL ** || ** AMMETERS **
 * CURRENT **
 * THROUGH **
 * AMPERES **
 * IN SERIES ** ||

2.11 describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how this can be investigated experimentally

NUMBER FOUR: **GUESS THE RESISTANCE ACTIVITY**

NUMBER FIVE: **CURRENT AGAINST VOLTAGE IN COMPONENTS ACTIVITY**

RESISTANCE (R): The amount that a component opposes the flow of current. R=V/I OHM (Ω): the resistance of a conductor where the current is 1 A when a PD of 1V is across it. OHM’S LAW: The current through a metallic conductor is directly proportional to the voltage across its ends if the temperature and other conditions are constant

2.12 describe the qualitative effect of changing resistance on the current in a circuit ACTIVITY SIX

media type="custom" key="12317232" width="100" height="100" 2.13 describe the qualitative variation of resistance of LDRs with illumination and of thermistors with temperature NUMBER SEVEN: INVESTIGA TION OF LDR AND THERMISTOR

[|ONLINE EXPERIMENT ON LDRS AT VIRTUAL EXPERIMENTS] 2.14 know that lamps and LEDs can be used to indicate the presence of a current in a circuit

2.15 recall and use the relationship between voltage, current and resistance: voltage = current × resistance V = I × R

2.16 understand that current is the rate of flow of charge

ELECTRIC CURRENT (I): The flow of electric charge. ELECTRIC CHARGE (Q): The cause of electric fields and currents. Either positive or negative. Q=It COULOMB (C): The unit of electric charge. When a current of 1A flows for 1s, 1C passes.

2.17 recall and use the relationship between charge, current and time: charge = current × time Q = I × t 2.18 recall that electric current in solid metallic conductors is a flow of negatively charged electrons ** 2.19 recall that: **
 * ** voltage is the energy transferred per unit charge passed **
 * ** the volt is a joule per coulomb **



POTENTIAL DIFFERENCE (V): When a source builds up an excess of electrons at the negative terminal, it is said to have a potential difference across its terminals (ie a current would flow if there were a circuit connection). It is also known as voltage and is a measure of energy transferred per coulomb flowing between two points.

VOLT (V): When 1 coulomb passes between two points and transfers 1 joule of energy, the potential difference between the points is 1 volt. 1V=1J/C. PD=Energy/Charge

EXAMPLES OF CALCULATIONS IN ENERGY AND PD **TRY THESE QUESTIONS (WITH ANSWERS) BEFORE YOU GO TO THE PRACTICE QUESTIONS LINK BELOW**
 * 1) What is the PD across five 2.0 V cells A) in series, and B) in parallel? [10 V; 2.0 V]
 * 2) What is the PD across a 10 kΩ resistor when the current through it is 0.2 A? [2 000 V]
 * 3) 240 C flows through a wire in 5 minutes. What is the current? [0.8 A]
 * 4) In a source, 32 J is converted to electrical energy when 2.5 C flows through it. What is the voltage of the source? [12.8 V]
 * 5) A current of 250 mA flows for 20.0 s through a source of 12.0 V. How much energy is converted? [60.0 J]

PRACTICE CALCULATIONS IN ENERGY AND PD

**REVISION RESOURCES FOR THIS SUB-TOPIC****SIMPLE CIRCUITS SLIDESHOW QUIZ**