Identify the correct statement
I. The flux can be altered by changing the shape of a coil in a magnetic field or rotating coil in a magnetic field such that the angle between B and A changes.
II. By changing the shape of a coil or the angle between B and A, an emf is induced in the coil. Which of the above statement(s) is/are correct?

Options

A. only I
B. only II
C. Both I and II
D. Neither I nor II

Answer

To solve the problem, we need to analyze the two statements provided and determine their correctness based on the principles of electromagnetic induction.

### Step-by-Step Solution:

1. **Understanding Magnetic Flux**:
- Magnetic flux (Φ) through a surface is defined as the product of the magnetic field (B) and the area (A) of the surface, taking into account the angle (θ) between the magnetic field and the normal to the surface.
- Mathematically, it is expressed as:
\[ \Phi = B \cdot A \cdot \cos(\theta) \]
- Here, θ is the angle between the magnetic field vector (B) and the area vector (A).

2. **Analyzing Statement I**:
- The first statement claims that the flux can be altered by changing the shape of the coil in a magnetic field or by rotating the coil such that the angle between B and A changes.
- Changing the shape of the coil alters the area (A), which directly affects the magnetic flux (Φ).
- Rotating the coil changes the angle (θ) between the magnetic field and the area vector, which also affects the magnetic flux.
- Therefore, **Statement I is correct**.

3. **Analyzing Statement II**:
- The second statement asserts that by changing the shape of the coil or the angle between B and A, an electromotive force (emf) is induced in the coil.
- According to Faraday's law of electromagnetic induction, an emf (E) is induced in a coil when there is a change in magnetic flux through it, expressed as:
\[ E = -\frac{d\Phi}{dt} \]
- Since we established that changing the shape of the coil or the angle changes the flux, it follows that the rate of change of flux (dΦ/dt) will not be zero.
- Thus, an emf will indeed be induced when these changes occur.
- Therefore, **Statement II is also correct**.

4. **Conclusion**:
- Both statements are correct. Hence, the correct option is that both Statement I and Statement II are correct.

### Final Answer:
Both Statement I and Statement II are correct.