Magnetic Flux

To solve the problem, we need to identify the correct unit of magnetic flux.

1. Definition of Magnetic Flux:
Magnetic flux ( ) is the total magnetic field passing through a given area. It is a scalar quantity and is mathematically given by:


where:
= magnetic field
= area
= angle between and normal to the surface

2. SI Unit of Magnetic Flux:
The SI unit of magnetic flux is the weber (Wb).

3. Understanding the Options:
- dyne: unit of force
- weber: unit of magnetic flux ✅
- oersted: unit of magnetic field strength
- gauss: unit of magnetic field (CGS system)

Final Answer:
The unit of magnetic flux is .

To solve the problem, we need to identify the law which states that the induced emf in a closed loop is equal to the rate of change of magnetic flux through the loop.

1. Understanding Faraday's Law of Electromagnetic Induction:
According to Faraday's Law, the magnitude of the induced emf in a closed circuit is directly proportional to the rate of change of magnetic flux through the circuit.

Mathematically:
where is the magnetic flux.

2. Distinguishing from Other Laws:
- Coulomb’s Law deals with electric force between charges.
- Lenz’s Law gives the direction of the induced current (negative sign in Faraday’s law).
- Newton’s Laws are laws of motion.

Final Answer:
The correct law is .