Topic: Electromagnetic Induction

6.04 understand the term magnetic field line

Around every magnet there is a region of space where we can detect magnetism (where magnetic materials will be affected).

This is called the magnetic field and in a diagram we represent this with magnetic field lines. 

The magnetic field lines should always point from north to south.

6.07 describe how to use two permanent magnets to produce a uniform magnetic field pattern

A uniform magnetic field is comprised of straight, parallel lines which are evenly spaced. Between two opposite charges on flat magnets, a uniform magnetic field is formed.

6.15 know that a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it and describe the factors that affect the size of the induced voltage

When a conductor (can be a wire, coil or just a piece of metal) experiences a changing magnetic field a potential difference or voltage is induced in it. The strength of the potential difference depends on the strength of the magnetic field, how fast it changes i.e. how fast the coil is spinning, and how much of the conductor is exposed to the field i.e. how many turns in the coil.

6.16 describe the generation of electricity by the rotation of a magnet within a coil of wire and of a coil of wire within a magnetic field, and describe the factors that affect the size of the induced voltage

Electricity can be generated by either moving a magnet inside a coil of wire or rotating a coil inside a permanent magnetic field.

 

Model answer for a generator (Rotating coil):

·         Coil is rotated within a magnetic field

·         As it turns the coil cuts the magnetic field lines.

·         This induces a voltage (or current) in the coil.

·         This can then be connected to an existing circuit.

·         In a generator, energy is being converted from kinetic (mechanical) energy into electrical energy.

·         The size of the induced voltage (or current) can be increased by:

·         Using a stronger magnet

·         Having more turns in the coil

·         Spinning/moving the coil faster.

 

Model answer for a generator (Rotating magnet)

·         Magnet is rotated within a coil

·         As it turns the coil cuts the constantly changing magnetic field lines from the magnet.

·         This induces a voltage (or current) in the coil.

·         This can then be connected to an existing circuit.

·         In a generator, energy is being converted from kinetic (mechanical) energy into electrical energy.

·         The size of the induced voltage (or current) can be increased by:

·         Using a stronger magnet

·         Having more turns in the coil

·         Spinning/moving the magnet faster.

 

6.17 describe the structure of a transformer, and understand that a transformer changes the size of an alternating voltage by having different numbers of turns on the input and output sides

AC current in the primary coil produces a changing magnetic field around the primary coil.

The iron core channels the changing field through the secondary coil.

The changing magnetic field induces a voltage in the secondary coil.

6.18 explain the use of step-up and step-down transformers in the large-scale generation and transmission of electrical energy

Step Up transformers increase the voltage – more secondary turns than primary

Step Down transformers decrease the voltage – more primary turns than secondary

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Section 1: Principles of chemistry

      a) States of matter

      b) Atoms

      c) Atomic structure

     d) Relative formula masses and molar volumes of gases

     e) Chemical formulae and chemical equations

     f) Ionic compounds

     g) Covalent substances

     h) Metallic crystals

     i) Electrolysis

 Section 2: Chemistry of the elements

     a) The Periodic Table

     b) Group 1 elements: lithium, sodium and potassium

     c) Group 7 elements: chlorine, bromine and iodine

     d) Oxygen and oxides

     e) Hydrogen and water

     f) Reactivity series

     g) Tests for ions and gases

Section 3: Organic chemistry

     a) Introduction

     b) Alkanes

     c) Alkenes

     d) Ethanol

Section 4: Physical chemistry

     a) Acids, alkalis and salts

     b) Energetics

     c) Rates of reaction

     d) Equilibria

Section 5: Chemistry in industry

     a) Extraction and uses of metals

     b) Crude oil

     c) Synthetic polymers

     d) The industrial manufacture of chemicals