Magnetic Fields and Electromagnetic Induction

• A current-carrying wire produces its own magnetic field, with the direction determined by Fleming's left hand rule (thumb points along the current, fingers curl around the wire).
• When two wires carrying currents are close together, they produce their own magnetic fields that interact with each other.
• The strength of the magnetic field produced depends on the length of the wire carrying the current.
• Magnetism is caused by moving charges or changing electric fields.
• If the wires carry equal currents but have different lengths, the longer wire will produce a stronger magnetic field than the shorter one.
• Electricity can be used to generate magnetism through electromagnets.
• Current flowing through the coil creates a magnetic field around it, which becomes stronger as more turns of wire are added.
• An electromagnet consists of an iron core wrapped with coils of wire connected to a battery.
• Flux is the same in each coil at all times
• Rate of change of flux is the same in both coils at all times.
• I$I_p V_p =$$I_s V_s$
• $V _s =$$N_s \frac{\Delta \phi}{\Delta t}$
• $\frac{N_p}{N_s} =$$\frac{V_p}{V_s}$
• A transformer consists of a primary and a secondary coil.
• A rotating coil in a uniform magnetic field had a sinusoidally changing flux linkage.
• $\varphi =$$BAN(2\pi ft)$
• $\omega =$$2\pi f$
• $\varphi =$$BAN \cos (\omega t)$
• If the current through the coil changes, then there will be an induced emf in the coil due to Faraday's law.
• Faraday’s Law states that the induced emf will be equal to the rate of change of flux linkage.
• $F =$$BIL$
• Tesla : The force acting per unit current per unit of length on a wire placed at right angles to the magnetic field
• When a conductor moves across or along a magnetic field, it experiences a force which can cause an electric current to flow around the circuit.
• The equation for force when considering magnetism, current and length is: $F =$$BIL$
• A generator converts mechanical energy into electrical energy by using the principle of electromagnetic induction.
• Transformers are used to increase or decrease voltage without changing power.
• An alternator works like a generator but produces AC instead of DC.
• In a transformer, the primary coil has more turns than the secondary coil so there is a step up in potential difference.