Select the incorrect statement about cathode rays.

Options

A. Deflected by electric and magnetic field
B. Stream of electron
C. Move with same speed as that of light
D. Travel in straight lines

Answer

To solve the question "Select the incorrect statement about cathode rays," we need to analyze each of the provided statements about cathode rays.

### Step-by-Step Solution:

1. **Understanding Cathode Rays**:
- Cathode rays are streams of electrons that are emitted from the cathode in a vacuum tube and move towards the anode.

2. **Evaluating the Statements**:
- **Statement 1**: "Deflected by electric and magnetic field."
- **Analysis**: This statement is correct. Cathode rays (electrons) are charged particles and will be deflected when placed in electric and magnetic fields due to the forces acting on them.

- **Statement 2**: "Stream of electrons."
- **Analysis**: This statement is also correct. Cathode rays consist of electrons, which are negatively charged particles.

- **Statement 3**: "Move with same speed as that of light."
- **Analysis**: This statement is incorrect. While cathode rays travel at high speeds, they do not move at the speed of light. The speed of light in a vacuum is approximately 3 x 10^8 m/s, which is faster than the speed of electrons.

- **Statement 4**: "Travel in straight lines."
- **Analysis**: This statement is correct. In the absence of electric and magnetic fields, cathode rays travel in straight lines.

3. **Identifying the Incorrect Statement**:
- After evaluating all the statements, we find that Statement 3 ("Move with same speed as that of light") is the incorrect statement regarding cathode rays.

### Conclusion:
The incorrect statement about cathode rays is:
**"Move with same speed as that of light."**