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What is electromagnetic induction? A magnet and a coil can be used to produce electricity - Leaving Cert Physics - Question d - 2008
Question d
What is electromagnetic induction? A magnet and a coil can be used to produce electricity. How would you demonstrate this? The electricity produced is a.c. Wha... show full transcript
Worked Solution & Example Answer:What is electromagnetic induction? A magnet and a coil can be used to produce electricity - Leaving Cert Physics - Question d - 2008
Step 1
What is electromagnetic induction?
Answer
Electromagnetic induction is the process through which an electromotive force (emf) or voltage is generated in a conductor when it is exposed to a changing magnetic field. This phenomenon occurs due to the relative motion between the magnetic field and the conductor. The induced emf is linked to the rate of change of magnetic flux through the coil, which is mathematically expressed as:
ext{emf} = - rac{d ext{Φ}}{dt}
where ( ext{Φ} ) represents the magnetic flux.
In simpler terms, as a magnet moves towards or away from a coil, or as the current in another coil changes, it induces a voltage in the coil due to the magnetic field's fluctuation.
Step 2
A magnet and a coil can be used to produce electricity. How would you demonstrate this?
Answer
To demonstrate the production of electricity using a magnet and a coil, follow these steps:
Apparatus:
- Coil of wire
- Magnet
- Galvanometer (to measure current)
Procedure:
- Connect the galvanometer to the ends of the coil.
- Hold the magnet stationary near the coil.
- Move the magnet toward the coil in a straight line, then pull it away.
- Observe the galvanometer; if current is induced, the needle will move, indicating the presence of electric current.
- Repeat the experiment by moving the magnet at varying speeds to see how it affects the generated current.
Observation/Conclusion:
As the magnet moves relative to the coil, an induced current flows through the galvanometer, demonstrating electromagnetic induction.
Step 3
The electricity produced is a.c. What is meant by a.c.?
Answer
The term 'a.c.' stands for alternating current. It refers to an electric current that periodically reverses direction. Unlike direct current (d.c.), where the flow of electric charge is constant and unidirectional, a.c. changes its direction and magnitude over time, typically in a sinusoidal pattern.
This type of current is commonly used in power supply systems because it is more efficient for long-distance transmission. As a result, it can be transformed to different voltages easily using transformers, which is not feasible with d.c.