Electromagnetism

The figure above shows the structure of a circuit breaker. A circuit breaker is an automatic switch that cut off current in a circuit when the current becomes too large. When the current in a circuit increases, the strength of the electromagnet will increase in accordance; this will pull the soft iron armature towards the … Read more

Types of Transformer There are 2 types of transformers, namely the step-up transformer the step-down transformer Step-up Transformer A step-up transformer is one where the e.m.f. in the secondary coil is greater than the e.m.f. in the primary coil. It is used to increases the potential difference. The number of windings in the secondary winding is … Read more

[This image is original released under GNU Free Documentation license ] What is the transformer? A transformer is a device that is used to raise or lower down the potential difference of an alternating current. Function: The function of a transformer is to increase or decrease the potential difference of an alternating current supply. Structure … Read more

The Effective Voltage for a Sinusoidal Alternating Current The maximum potential difference supplied by an a.c source is known as the peak voltage VP. The effective potential difference for an a.c is equal to the potential difference of an alternating current if both results in the same heating effect. The effective potential difference for a.c … Read more

Direct Current Direct current is a uniform current flowing in one fixed direction in a circuit Direct current (d.c) is usually supplied by acid-based batteries or dry cells.  A common example of acid-based (electrolyte) batteries is the car battery.  The figure below shows the graph of current supplied by a dry cell over time. Alternating … Read more

A generator can be modified to an a.c generator by replacing its commutators with two (separate) slip rings. The two slip rings rotate in tandem with the armature.  Carbon brushes connect the armature to the external circuit. The armature is initially at the vertical position. No magnetic flux is cut and hence no induced current … Read more

The figure above shows the illustration of a simple direct current (d.c.) generator. You should notice that the simple d.c generator is almost the same as the d.c. motor except that the battery in the d.c. motor is removed and replaced by a resistor. The direct current generator produces electric current (or voltage) base on … Read more

When a bar magnet is inserted into a solenoid, the solenoid will cut the magnetic flux of the bar magnet. This will induce a current and emf in the solenoid. The induced current will produce another magnetic field around it. The pole of the magnetic field and direction of the induced current can be determined … Read more

When a straight conductor (or wire) moves and cut a magnetic field, emf will be induced across the conductor. If the conductor is in a complete circuit, the current will flow in the conductor. The direction of the current induced can be determined by using Fleming’s Right Hand Rule, as explained in the video below. … Read more

There are 2 principal laws of electromagnetic induction: Faraday’s law Lenz’s law Faraday’s Law The magnitude of the induced e.m.f is determined by Faraday’s Law. Faraday’s Law states that the magnitude of the induced e.m.f is directly proportional to the rate of change of magnetic flux through a coil or alternatively the rate of the … Read more