Transformers

• Transformers use electromagnetic induction to change the voltage of alternating currents.
• The voltage and current changes in transformers can be calculated, as the power transfer is constant.
• A transformer is an electrical device that increases, or decreases, the potential difference (voltage) of an alternating current.
• The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit.
• The potential difference across a cell, electrical supply or electrical component is measured in volts (V).
• A basic transformer is made from two coils of wire, a primary coil from the alternating current (ac) input and a secondary coil leading to the ac output.
• The coils in a transformer are not electrically connected, instead, they are wound around an iron core.
• The iron core in a transformer increases the strength of the magnetic field.
• The changing magnetic field in a transformer induces a changing potential difference in the secondary coil.
• The induced potential difference in a transformer produces an alternating current in the external circuit.
• Transformers can only work with alternating current.
• Transformers use electromagnetic induction to change the voltage of alternating currents.
• The voltage and current changes can be calculated, as the power transfer is constant.
• Transformers use electromagnetic induction to change the voltage of alternating currents.
• An electrical device that increases, or decreases, the potential difference (voltage) of an alternating current is known as a transformer.
• The voltage and current changes in transformers can be calculated, as the power transfer is constant.
• The ratio of potential differences on the transformer is the same as the ratio of the numbers of turns on the coils.
• Power in transformers is calculated using the equation: power = potential difference × current (P = V I).
• Potential difference (V) is measured in volts (V), current (I) is measured in amperes - also referred to as amps (A), and power (P) is measured in watts (W).
• A transformer is an electrical device that increases, or decreases, the potential difference (voltage) of an alternating current.
• A mains (230 volt) transformer has 11,500 turns on its primary coil and 600 turns on its secondary coil.
• If a transformer is 100 per cent efficient, the power output from the transformer can be calculated using the equation: potential difference across primary coil × current in primary coil = potential difference across secondary coil × current in secondary coil (V_s × I_s = V_p × I_p).
• The transformer in the example above is a step-down transformer because there are fewer turns on the secondary coil, and there is a smaller voltage on the secondary coil.
• A step-down transformer converts 11,500 V into 230 V.
• The power output from a step-down transformer is used to run a 2,000 W kettle.
• The National Grid is the network that connects all of the power stations in the country to make sure that everywhere has access to electricity.
• The higher the current in a cable, the greater the energy transferred to the surroundings by heating.
• To reduce energy transfers to the environment, the National Grid uses step-up transformers to increase the voltage from power stations to thousands of volts, which lowers the current in the transmission cables.
• Step-down transformers are then used to decrease the voltage from the transmission cables, so it is safer to distribute to homes and factories.