Electromagnetic Induction Flashcards
How is electricity induced in a wire?
Electricity can be induced in a wire by placing it in a magnetic field. This is known as electromagnetic induction - creating electricity using a magnet. It works because the magnetic field around the coil is changing when the coil ‘cuts through’ the magnetic field line. It can be done by moving a bar magnet inside a coil of wire or by moving a coil of wire in a magnetic field. Because the magnet is being moved back and forth this changes the direction of the current creating alternating (a.c.) current.
What is the opposite of the motor effect?
Electromagnetic induction is the opposite of the motor effect. The motor effect is when an electric current produces a movement of a wire (due to the interaction of magnetic fields). Electromagnetic induction is when movement of a wire (or a magnet) creates an electric current.
How can the size of the induced voltage be increased?
The size of the induced voltage will increase if: the strength of the magnet is increased the number of turns on the coil is increased the magnet is moved into the coil of wire faster.
What do transformers do?
Transformers are electrical devices that change the voltage of alternating current (AC). They are essential for the efficient transmission of electrical energy over long distances. In power stations the voltage is increased to reduce the current and minimise energy loss in transmission lines. When the electricity reaches homes the voltage is reduced to a safe level using another transformer.
What are the components of a transformer?
A transformer consists of two coils of wire - the primary coil and the secondary coil - wrapped around a rectangular iron core. The core is usually made of laminated iron to reduce energy losses due to eddy currents. The primary coil receives the alternating current
What is a step-up transformer and how does it work?
A step-up transformer increases the voltage of an alternating current. This is achieved by having more turns on the secondary coil than the primary coil. The increased number of turns on the secondary coil results in a higher voltage output. Step-up transformers are used in power stations to increase the voltage for efficient transmission.
What is a step-down transformer and how does it work?
A step-down transformer decreases the voltage of an alternating current. It works by having fewer turns on the secondary coil compared to the primary coil. The decreased number of turns on the secondary coil results in a lower voltage output. Step-down transformers are used to reduce the voltage to a safe level before electricity is supplied to homes or businesses.
What is the principle of conservation of energy in transformers?
Transformers are nearly 100% efficient meaning the power input is equal to the power output. This principle can be expressed using the equation: power = voltage × current. Therefore
What is the relationship between the number of turns and voltage in transformers?
The voltage ratio between the primary and secondary coils is directly proportional to the ratio of the number of turns on the coils. This relationship is given by the equation: Vp/Vs = Np/Ns
