1. Who discovered electromagnetic induction?
Answer:
Explanation:
Electromagnetic induction was discovered by Michael Faraday in 1831.
2. Faraday's law of electromagnetic induction is related to the _______ of magnetic flux linking a circuit.
Answer:
Explanation:
Faraday's law relates the induced electromotive force (EMF) in any closed circuit to the negative rate of change of the magnetic flux through the circuit.
3. Lenz's law is a manifestation of the conservation of:
Answer:
Explanation:
Lenz's law, which states that the direction of induced current is such as to oppose the change causing it, is a manifestation of the conservation of energy.
4. A coil has a resistance of 10 ohms and an inductance of 2H. If the current changes at a rate of 3A/s, the induced emf is:
Answer:
Explanation:
Induced emf = L * (di/dt) = 2H * 3A/s = 6V
5. The phenomenon of inducing emf by changing the number of magnetic lines of force around a conductor is called:
Answer:
Explanation:
Self-induction is the phenomenon where a change in current in a coil induces an emf in the same coil.
6. The unit of magnetic flux is:
Answer:
Explanation:
The SI unit of magnetic flux is Weber (Wb).
7. The phenomenon in which an emf is induced in a coil due to a change in current in a neighboring coil is termed as:
Answer:
Explanation:
Mutual induction refers to the process where a change in current in one coil induces an emf in a neighboring coil.
8. A transformer works on the principle of:
Answer:
Explanation:
A transformer operates based on the principle of mutual induction.
9. Which of the following is not a factor affecting induced emf in a coil?
Answer:
Explanation:
The induced emf is independent of the resistance of the coil. It depends on the other given factors.
10. In electromagnetic induction, if the circuit is closed:
Answer:
Explanation:
If the circuit is closed and there's an induced emf, current will flow through the circuit.
11. The core of a transformer is made of:
Answer:
Explanation:
The core of a transformer is made of soft iron as it has high magnetic permeability and low hysteresis loss.
12. Eddy currents are:
Answer:
Explanation:
Eddy currents are induced circulating currents produced in a conductor when it is placed in a changing magnetic field, typically due to relative motion between the magnet and conductor.
13. Which device can be used to convert mechanical energy into electrical energy?
Answer:
Explanation:
A dynamo is a device that converts mechanical energy into electrical energy through electromagnetic induction.
14. The magnitude of induced emf can be increased by:
Answer:
Explanation:
The magnitude of induced emf can be increased by increasing the area of the coil, the number of turns in the coil, the strength of the magnetic field, and the speed of relative motion.
15. Eddy currents result in:
Answer:
Explanation:
Eddy currents lead to resistive heating within the conductor, resulting in energy loss.
16. The back emf in a motor:
Answer:
Explanation:
As the motor gains speed, the rate of change of magnetic flux also increases, leading to an increase in back emf.
17. In a generator, mechanical energy is converted into:
Answer:
Explanation:
In a generator, mechanical energy is converted into electrical energy through electromagnetic induction.
18. If a coil of wire is moved through a magnetic field:
Answer:
Explanation:
Voltage or emf can be induced in a wire moving through a magnetic field irrespective of whether the wire is part of a closed circuit or not.
19. The phenomenon where an emf is induced in a body by its own changing magnetic environment is termed:
Answer:
Explanation:
When an emf is induced in a body due to its own changing magnetic environment, it is called self-induction.
20. The purpose of laminating the core in transformers and machines is to:
Answer:
Explanation:
The core is laminated to interrupt the path of the eddy currents and reduce their magnitude, which in turn minimizes the associated energy losses.