Topic 13 - EM Induction Flashcards
What is Electromagnetic Induction?
- Creating an electric current by moving a magnet or a coil of wire relative to each other
Factors Affecting Potential Difference in Electromagnetic Induction:
- Rate of Change of all Magnetic Field passing through a surface
- Number of Turns in the Coil
- Strength of the Magnetic Field (MFD)
- Area of the Coil
How do the magnetic field produced oppose the original change ?
- After the (original) change of the magnets and the coil of wire, the coil produces an opposite magnetic field
Electromagnetic induction is used in alternators to generate current which:
- alternates in direction
Electromagnetic induction is used in
dynamos to generate current which:
- is direct
How do microphone convert the pressure variations in sound waves into variations in current in electrical circuits?
- Sound waves cause diaphragm to vibrate
- This causes coil (connecting to microphone) to vibrate
- Coil cuts through field lines, inducing an alternating p.d, and therefore, alternating current
How can an alternating current in one circuit induce a current in another circuit in a transformer
- Creates a magnetic field when current flows through. This induces a voltage in the second coil
A transformer can change what in an alternating voltage?
- its size
Why is electrical energy transferred at high voltages from power stations, and then transferred at lower voltages in each locality?
- improves the efficiency by reducing heat loss in transmission lines
Why are step-up and step-down transformers used in the transmission of electricity in the national grid
Step up:
- Before entering national grid
- Reduces energy losses due to resistance in the transmission lines
Step down:
- Nearing destinations
- Make the electricity safe and suitable for use
