Electricity

• A diode is a component that only act as a conductor when the current flows in One Direction
• A thermistor is a component that decreases in resistance as the temperature increases
• A light dependent resistor (LDR) is a component that reduces in resistance as the light intensity increases
• components in series are connected in a loop by wires. If there is a break in the loop all the components will turn off.
• Components in parallel are in separate loops, when one component breaks all the others will still work
• An ammeter must always be connected in series with the component we want to find the current through
• A voltmeter must be connected in parallel with the component over which the potential difference is being measured across
• Electric current is the flow of electrical charge. We measure current using an ammeter in ampers (amps) with the symbol A.
• The charge carriers in an electrical current are electrons
• The size of the current is the rate of flow of electrical charge
• Electrical charge is measured in coulombs (C)
• We calculate the charge passing a point in a circuit by doing: charge🟰 Current ✖️ _. time.
• Electrical resistance is measured in ohms and is the opposite to current flow. The harder it is for electrons to flow the higher the resistance.
• resistance increases when: cross-sectional area decreases, temperature increases, length of wire increases and it can also change between materials.
• In a parallel circuit total resistance is lower than the lowest resistor.
• In a series circuit if you add all the resistance together you will get the total resistance.
• As the length of wire increases the resistance increases this is because the electrons have further to travel through the metal ions (more metal ions).
• As the thickness of the wire increases the resistance will decrease because it is easier for the ions to pass through.
• Ohms law states that the potential difference across a conductor is directly proportional to the current flowing through it: Potential difference (V in V) 🟰 current (I in A) ✖️ Resistance (R in ohms )
• As temperature increases resistance decreases this is because increasing the temperature, it frees more electrons to carry the current.
• As light intensity increases resistance decreases.
• In series the current is equal at every point in the circuit.
• In parallel the current splits, branches with more resistance have less current
• In series the potential difference is shared between components.
• In parallel each branch has the same potential difference as the source
• Potential difference is the measure of difference in energy
• The potential difference and current from a cell will always have a fixed positive and fixed negative side.
• In alternating-current (AC) the charge carriers constantly change directions.
• Mains electricity AC is at a frequency of 50 Hz and a voltage of 230V.
• An AC graph will always cross the middle line.
• In direct current (DC) the charge carriers will always move in the same direction. A cell will always provide a DC.
• An AC graph will not cross the middle line / x axis
• Electricity is the flow of electrons.
• Power 🟰 energy transferred ➗ time
• Power 🟰 current squared ✖️ resistance
• P 🟰 V ✖️I
• dissipated power is the power lost by a resistor.
• Current is the flow of charge.
• Potential difference. 🟰. Current. ✖️ Resistance
• V 🟰 I ✖️ R