Mention the charge, mass and e/m ratio for an electron.

Answer

To answer the question regarding the charge, mass, and e/m ratio for an electron, we will break down the solution into clear steps.

### Step-by-Step Solution

1. **Charge of an Electron**:
- The charge of an electron is negative.
- The value of the charge is represented as \(-e\).
- The magnitude of the charge is \(e = 1.6 \times 10^{-19}\) coulombs.
- Therefore, the charge of an electron is:
\[ \text{Charge of electron} = -1.6 \times 10^{-19} \text{ C} \]

2. **Mass of an Electron**:
- The mass of an electron is a known constant.
- It is given as:
\[ \text{Mass of electron} = 9.1 \times 10^{-31} \text{ kg} \]

3. **E/M Ratio for an Electron**:
- The e/m ratio (charge-to-mass ratio) is calculated using the formula:
\[ \frac{e}{m} = \frac{\text{Charge}}{\text{Mass}} \]
- Substituting the values we have:
\[ \frac{e}{m} = \frac{1.6 \times 10^{-19} \text{ C}}{9.1 \times 10^{-31} \text{ kg}} \]
- Performing the calculation:
\[ \frac{e}{m} \approx 1.758 \times 10^{11} \text{ C/kg} \]
- Therefore, the e/m ratio for an electron is approximately:
\[ \frac{e}{m} \approx 1.758 \times 10^{11} \text{ C/kg} \]

### Summary of Results
- **Charge of Electron**: \(-1.6 \times 10^{-19} \text{ C}\)
- **Mass of Electron**: \(9.1 \times 10^{-31} \text{ kg}\)
- **E/M Ratio**: \(1.758 \times 10^{11} \text{ C/kg}\)