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4.3 In a certain circuit having two parallel branches the instantaneous branch circuits are represented by:

```
i_(1)=30Sin(wt+(\pi )/(4))
i_(2)=30Sin(wt-(\pi )/(4))
```

4.3.1 Calculate the total current and write it in the form:

`i=I_(max)Sin(wt+\theta )`

4.3.2 Illustrate these currents by drawing a phasor diagram. [20] QUESTION 5 5.1 At what speed must a FOUR pole alternator be driven to produce an EMF having a frequency of 50 Hz ? 5.2 Which motor is superior in efficiency, and the most extensively used of all types of electric motors? 5.3 An impedance of

`(30)/(_(45))\deg `

ohms and an impedance of

`(30)/(_(-))45\deg `

ohms are connected in parallel to a 300 volt, 50 Hz supply. Calculate the following: 5.3.1 The total impedance 5.3.2 The current in each branch 5.3.3 The current flowing in the circuit 5.3.4 The overall power factor and 5.3.5 Draw the phasor diagram to present the current in the circuit. 5.4 A milli-ammeter with a coil resistance of 10 ohms indicates a full-scale deflection when a current of 2000 mA flows through it. Determine the value of the series resistances required to enable the instrument to be used as a: 5.4.1 40 V voltmeter 5.4.2 3 A ammeter

`(2\times 2)`

5.5 Why coal-fired power stations are normally built far away from the main load points? (2) [20]