Modern train are based on maglev technology in which trains are magntically levitated, which runs its `EDS` maglev system. There are coils on both sides of wheels. Due to motion of the train, current induces in the coil of track which levitate it. This is in accordance with Lenz's law. If train lowers down then due to Lenz's law, repulsive force increase due to which train gets uplifted and if it goes much higher then there is a net downward force due to gravity. The advantage of Maglev trains in that there is no friction between the train and the track, thereby reducting power consumption and enabling the train to attain very high speeds. Disavantage of Maglev train is that as it slows down, the electromagnetic forces decreases and it becomes difficult to keep it levitaited and as it moves forward according to Lenz's law there ia an electromagnetic drag force.
Which force causes the train to elevate up?

Options

A. Electrostatic force
B. Time varying electing field
C. Magnetic force
D. Induced electric field

Explanation

To solve the question regarding the force that causes the train to elevate in the context of maglev technology, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Maglev Technology**:
- Maglev (magnetic levitation) technology allows trains to float above the tracks using magnetic forces. This eliminates friction, allowing for high speeds.

2. **Role of Coils and Current Induction**:
- The train has coils on both sides of its wheels. As the train moves, it induces a current in the coils of the track. This induced current is essential for creating the magnetic fields necessary for levitation.

3. **Application of Lenz's Law**:
- According to Lenz's Law, the direction of induced current will oppose the change that created it. When the train moves downward, the current induced in the track coils creates a magnetic field that produces a repulsive force, pushing the train upward.

4. **Identifying the Force Responsible for Elevation**:
- The question asks which force causes the train to elevate. The repulsive force generated by the interaction of the magnetic fields (from the train and the track) is what lifts the train.

5. **Evaluating the Options**:
- A) Electrostatic Force: This is not applicable as maglev technology relies on magnetic forces, not electrostatic.
- B) Time-varying Electric Field: While this relates to electromagnetic induction, it does not directly cause elevation.
- C) Magnetic Force: This is the force that results from the interaction between the magnetic fields of the train and the track, causing the train to levitate.
- D) Induced Electric Field: This is a result of changing magnetic fields but does not directly cause elevation.

6. **Conclusion**:
- The correct answer is **C) Magnetic Force**, as it is the magnetic repulsion that elevates the train.

### Final Answer:
The force that causes the train to elevate up is **C) Magnetic Force**.