## 19 January 2019

### Active Power

• It is defined as the product of RMS voltage, RMS current and cosine of angle between voltage vector and current vector.

P = VI Cos F

## 25 October 2018

### Properties of Heating Material

The heating element should have following properties.

### High specific resistance

• As the specific resistance of the material should be kept high, the length of material requires for particular resistance is short.
R = ρL / a
Where ρ is resistivity of material

### Coulomb Law

• When two charged bodies place very close to each other, it experience a mechanical force.

### According to Coulomb’s law

• The force between charges bodies is directly proportional to product of charges, inversely proportional to square of distance between them and nature of medium surrounding them.

## 20 October 2018

### Compare Inverter AC and Non - Inverter AC

• The inverter 1 Ton AC will run continuously but draws as much power that is required to keep the room at desired cooling level. The Non inverter 1 Ton AC will always run at peak power requirement when the compressor is ON.
• The inverter AC works on variable speed compressor which means that its speed decreases when the temperature of room is right or lower and speed up when the

### Solid conductors

• The cross – section of the solid conductors are small because it is very difficult to handle it due to higher weight. It may break at the some point due to wind pressure in long span. ( Span is defined as the distance between two towers ).

## 29 September 2018

### Starting torque

• It is torque developed by the synchronous motor when name plate voltage is applied to its armature winding. It is also called as breakdown torque.
• It may as low as 10% in the case of centrifugal pump.

## 4 April 2018

### Brake Test

• It is direct test useful to find efficiency of small DC Motor.

### Theory

• The output power of the DC Motor is measured by applying brake to a pulley.
• One rope is wound round the pulley and its two ends are attached to spring balances W1 and W2