https://file.aiquickdraw.com/mathbot/file/1725566834200mu4v2xhm.pdf

Sure, let's look at Question 9 from the provided document:

---

**QUESTION 9**

9.1 The diagram below is a simplified representation of a DC motor. The current in the coil is in the direction XY.

9.1.1 Name the component that ensures that the coil rotates continuously in ONE DIRECTION. (1)

9.1.2 In which direction will the coil rotate? Write clockwise or anti-clockwise. (1)

9.1.3 Write down the energy conversion which takes place while the motor is working. (2)

9.2 An AC generator, producing a maximum voltage of 320 V, is connected to a heater of resistance 35 Ω.

9.2.1 Write down the structural difference between an AC generator and a DC generator. (2)

9.2.2 Calculate the root mean square (rms) value of the voltage. (2)

9.2.3 Calculate the root mean square (rms) value of the current in the heater. (4)

---

Let's solve each part of Question 9 step-by-step:

### 9.1 DC Motor

#### 9.1.1 Component for Continuous Rotation
The component that ensures that the coil of a DC motor rotates continuously in one direction is the **commutator**. 

#### 9.1.2 Direction of Rotation
To determine the direction of rotation (clockwise or anti-clockwise), we need to apply Fleming’s Left-Hand Rule. According to the rule, if the current is in the direction XY, and considering the conventional setup of a DC motor, the coil will rotate **clockwise**.

#### 9.1.3 Energy Conversion
The energy conversion that takes place while the motor is working is from **electrical energy to mechanical energy**.

### 9.2 AC Generator

#### 9.2.1 Structural Difference
The main structural difference between an AC generator and a DC generator is:

- **AC Generator:** Uses slip rings to maintain continuous contact with the rotating coil.
- **DC Generator:** Uses a commutator to reverse the direction of current and produce a unidirectional current.

#### 9.2.2 RMS Value of Voltage
Given the maximum voltage \( V_{max} = 320 \text{ V} \):

The root mean square (rms) value of the voltage is calculated as:
\[ V_{rms} = \frac{V_{max}}{\sqrt{2}} \]
\[ V_{rms} = \frac{320}{\sqrt{2}} \]
\[ V_{rms} = 320 \times \frac{1}{\sqrt{2}} \]
\[ V_{rms} \approx 226.27 \text{ V} \]

#### 9.2.3 RMS Value of Current
Given the resistance \( R = 35 \ \Omega \) and \( V_{rms} = 226.27 \text{ V} \):

The rms value of the current is calculated using Ohm's Law:
\[ I_{rms} = \frac{V_{rms}}{R} \]
\[ I_{rms} = \frac{226.27}{35} \]
\[ I_{rms} \approx 6.46 \text{ A} \]

---

Would you like more details or have any questions about these solutions?

### 5 Questions Related to the Topic:
1. What is the role of brushes in a DC motor?
2. How does the back emf affect the operation of a DC motor?
3. Explain the working principle of an AC generator.
4. How does the frequency of an AC generator affect the rms values of voltage and current?
5. What are the typical materials used for the commutator and brushes in DC motors?

### Tip:
Always remember that in an AC circuit, the rms values of voltage and current are crucial for calculating power, as they represent the effective values that do the actual work.

Explore detailed solutions to Question 9 from the Grade 12 Physical Sciences Paper 1. Learn about the working principles of DC motors and AC generators, energy conversion, and calculations of RMS values of voltage and current. Ideal for Grade 12 students preparing for exams.

Math Problem Statement

Solution

Ask a new question for Free

By Image

Math Problem Analysis

Mathematical Concepts

Formulas

Theorems

Suitable Grade Level

Related Recommendation