# About this site – Learn Physics online

This website (Mini Physics) offers O and A Level physics revision notes for you to learn Physics online. O Level is equivalent to American High School Diploma and A Level is equivalent to Advanced Placement. If you spot any mistakes in my explanation, please email the site administrator at miniphysics@hotmail.com with the relevant web address and […]

### Power

Power is defined as the rate of work done or energy converted with respect to time. $P = \frac{W}{t}$ OR $P = \frac{E}{t}$, where W = work, t = time, E = Energy SI Unit for power is watt (W), scalar quantity Another useful equation for power: P = Fv, where F = force, v = […]

### Energy

Energy of a system is defined as its capacity to do work. SI unit : joules (J) Scalar Quantity Energy can be converted from one form to another. It can also be transferred from one body to another through work done and/or heat exchanges. The Principle of conservation of energy states that energy cannot […]

### Work

Work is done when a force moves the object in the direction of the force and is given by the product of the force and the distance moved in the direction. W = Fs , Where W= Work, F = Constant Force (N), S = Distance moved in the direction of the force (m) SI Unit for work […]

### Work, Energy and Power (A level)

Work is done when a force moves the object in the direction of the force and is given by the product of the force and the distance moved in the direction. W = Fs , Where W= Work, F = Constant Force (N), S = Distance moved in the direction of the force (m) SI […]

### Reading kinematics graphs

For a distance-time graph, the distance never decreases. The gradient of a distance-time graph is the instantaneous speed of the object. When the object is stationary, the distance-time graph will be horizontal. The above figure shows the displacement-time graph, velocity-time graph and acceleration-time graph for the respective state of motion. Gradient of […]

### Workings of a Transformer

A transformer is a device that changes a high alternating voltage at low current to a low alternating voltage at high current or vice versa. Structure of transformer: Primary coil: Connected to primary input voltage ($V_{p}$) with turns ($N_{p}$) Secondary coil: connected to load with output voltage ($V_{s}$) with turns ($N_{s}$) Soft-iron core: The coils […]