Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; plgContentJComments has a deprecated constructor in /var/www/astarmathsandphysics/plugins/content/jcomments/jcomments.php on line 25 Call Stack: 0.0000 360656 1. {main}() /var/www/astarmathsandphysics/index.php:0 0.1077 1209256 2. Joomla\CMS\Application\SiteApplication->execute() /var/www/astarmathsandphysics/index.php:49 0.1077 1209256 3. Joomla\CMS\Application\SiteApplication->doExecute() /var/www/astarmathsandphysics/libraries/src/Application/CMSApplication.php:267 0.2086 4189696 4. Joomla\CMS\Application\SiteApplication->dispatch() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:233 0.2100 4217040 5. Joomla\CMS\Component\ComponentHelper::renderComponent() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:194 0.2108 4234752 6. Joomla\CMS\Component\ComponentHelper::executeComponent() /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:356 0.2110 4265272 7. require_once('/var/www/astarmathsandphysics/components/com_content/content.php') /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:381 0.2120 4287992 8. ContentController->execute() /var/www/astarmathsandphysics/components/com_content/content.php:42 0.2120 4287992 9. ContentController->display() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:710 0.2580 4959888 10. ContentController->display() /var/www/astarmathsandphysics/components/com_content/controller.php:113 0.2617 5152040 11. Joomla\CMS\Cache\Controller\ViewController->get() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:663 0.2623 5172968 12. ContentViewArticle->display() /var/www/astarmathsandphysics/libraries/src/Cache/Controller/ViewController.php:102 0.2734 5362616 13. Joomla\CMS\Plugin\PluginHelper::importPlugin() /var/www/astarmathsandphysics/components/com_content/views/article/view.html.php:189 0.2735 5362872 14. Joomla\CMS\Plugin\PluginHelper::import() /var/www/astarmathsandphysics/libraries/src/Plugin/PluginHelper.php:182

Transformers

Transformers have the effect of increasing or decreasing the voltage in a circuit. We may want to increase it – using a step up transformer - because for example, electricity transmission over long distances at high voltage over the National Grid means lower energy losses than electricity transmission at lower voltages. We would transform down to a lower and safer voltage – using a step down transformer - to supply it into people's houses. A typical transformer consists of loops of wire on an iron core as shown.

Transformers only work on ac circuits ie when the input voltage is an alternating voltage. The process is this:

  • An alternating current in the primary circuit on the leftinduces an changing magnetic field in the transformer core accordingto Faraday's Law and Lenz's Law.

  • This changing magnetic field in the core induces a current inthe secondary coil, again according to Faraday's and Lenz's Laws.

For a perfect transformer, such that there are no energy losses, so that the efficiency is 100%, we may use the equations,

and

In fact transformers are not 100% efficient. We may reduce energy losses by

Laminating the transformer core. The changing magnetic field induces eddy currents in the core itself. Since the core has resistance, energy losses will result here. If we laminate the fore reduces the eddy currents.

The wires in the primary and secondary coils have resistance. We could use thicker wires. Maybe superconducting wires may appear in the next few years.

Each time the core is magnetized and demagnetized, hysteresis losses result. We reduce these by using a soft iron core, which is easily magnetized and demagnetized.

Add comment

Security code
Refresh