Question: c) When voltage if first applied to a motor and it is not rotating, the xI of a motor is very low. If the xI of this motor at starting is 10 Ω, what is the starting current of the motor?
1. **Problem Statement:**
We are given the starting reactance $x_I = 10\ \Omega$ of a motor when voltage is first applied and the motor is not rotating. We need to find the starting current of the motor.
2. **Relevant Formula:**
In a series circuit, the starting current $I_{start}$ can be found using Ohm's Law:
$$I_{start} = \frac{V}{Z}$$
where $V$ is the applied voltage and $Z$ is the total impedance.
3. **Assumptions and Simplifications:**
Since the motor is not rotating, the back EMF is zero, and the impedance is dominated by the reactance $x_I$ and any resistance $R$ present.
4. **Given Data:**
- Reactance $x_I = 10\ \Omega$
- Voltage $V$ is not explicitly given, so we assume it as $V$ volts.
5. **Calculating Starting Current:**
If resistance $R$ is negligible or unknown, the impedance $Z$ is approximately equal to the reactance:
$$Z \approx x_I = 10\ \Omega$$
Therefore,
$$I_{start} = \frac{V}{10}$$
6. **Interpretation:**
The starting current depends on the applied voltage $V$. For example, if $V = 120$ volts,
$$I_{start} = \frac{120}{10} = 12\ \text{amperes}$$
**Final answer:**
The starting current of the motor is $$I_{start} = \frac{V}{10}$$ amperes, where $V$ is the applied voltage.