A circular loop of radius `r`, having `N` turns of a wire, is placed in a uniform and constant magnetic field `B`. The normal of the loop makes an angle `theta` with the magnetic that the angle `theta` is constant. Choose the correct statement from the following.

Options

A. (a) emf in the loop is `Nbomegar^(2)//2 cos theta`.
B. (b) emf induced in the loop is zero.
C. (c ) emf must be induced as the loop crosses magnetic lines.
D. (d) emf must not be induced as flux does not change with time.

Explanation

To solve the problem, we need to analyze the situation of a circular loop placed in a uniform magnetic field and determine the induced electromotive force (EMF) based on the given conditions.

### Step-by-Step Solution:

1. **Understanding the Setup**:
- We have a circular loop of radius \( r \) with \( N \) turns of wire.
- The loop is placed in a uniform magnetic field \( B \).
- The normal to the loop makes a constant angle \( \theta \) with the magnetic field.

2. **Magnetic Flux Calculation**:
- The magnetic flux \( \Phi \) through one turn of the loop is given by the formula:
\[ \Phi = B \cdot A \cdot \cos(\theta) \]
- Here, \( A \) is the area of the loop, which for a circular loop is:
\[ A = \pi r^2 \]
- Therefore, the magnetic flux through one turn becomes:
\[ \Phi = B \cdot (\pi r^2) \cdot \cos(\theta) \]

3. **Total Magnetic Flux for N Turns**:
- Since there are \( N \) turns, the total magnetic flux \( \Phi_{\text{total}} \) through the loop is:
\[ \Phi_{\text{total}} = N \cdot \Phi = N \cdot B \cdot (\pi r^2) \cdot \cos(\theta) \]

4. **Analyzing Change in Magnetic Flux**:
- The problem states that the angle \( \theta \) is constant, and since \( B \), \( r \), and \( N \) are also constant, the total magnetic flux \( \Phi_{\text{total}} \) remains constant over time.

5. **Applying Faraday's Law of Electromagnetic Induction**:
- According to Faraday's law, the induced EMF \( \mathcal{E} \) in the loop is given by:
\[ \mathcal{E} = -\frac{d\Phi_{\text{total}}}{dt} \]
- Since the magnetic flux is constant (i.e., \( \frac{d\Phi_{\text{total}}}{dt} = 0 \)), we find that:
\[ \mathcal{E} = 0 \]

6. **Conclusion**:
- Since the induced EMF is zero, we can conclude that:
- No EMF is induced in the loop because the magnetic flux does not change with time.
- Therefore, the correct statements are:
- Option 2: EMF is zero.
- Option 4: No EMF will be induced as flux does not change with time.

### Final Answer:
The correct options are 2 and 4.