Which of the following is not the property of a cathode rays

Options

A. it produces heating effect
B. it does not deflect in electric field
C. its casts shadow
D. it produces fluorescence

Answer

To determine which of the following is not a property of cathode rays, we will analyze each option provided.

### Step 1: Understand the properties of cathode rays
Cathode rays are streams of electrons observed in vacuum tubes. They possess several well-known properties that we can evaluate against the options given.

### Step 2: Evaluate each option
1. **Produces heat effect**:
- Cathode rays do produce heat when they strike a surface. The kinetic energy of the electrons is converted into thermal energy, causing the surface to heat up.
- **Conclusion**: This statement is true.

2. **Does not deflect in electric field**:
- Cathode rays, which are negatively charged electrons, do deflect in electric and magnetic fields. When placed in an electric field, they will move towards the positive plate, indicating deflection.
- **Conclusion**: This statement is false.

3. **Casts shadow**:
- Cathode rays are indeed invisible, but they can cast sharp shadows when they encounter an obstacle. This is due to the straight-line motion of the electrons.
- **Conclusion**: This statement is true.

4. **Produces fluorescence**:
- Cathode rays can cause certain materials to fluoresce when they strike them. This is a well-documented property of cathode rays.
- **Conclusion**: This statement is true.

### Step 3: Identify the incorrect property
From our evaluation, the only statement that does not hold true is the second one: "does not deflect in electric field." Therefore, this is the property that is not associated with cathode rays.

### Final Answer
The property that is not associated with cathode rays is: **"does not deflect in electric field."**

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