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: 0.0001 361936 1. {main}() /var/www/astarmathsandphysics/index.php:0 0.0482 1210568 2. Joomla\CMS\Application\SiteApplication->execute() /var/www/astarmathsandphysics/index.php:49 0.0482 1210568 3. Joomla\CMS\Application\SiteApplication->doExecute() /var/www/astarmathsandphysics/libraries/src/Application/CMSApplication.php:267 0.1218 4047832 4. Joomla\CMS\Application\SiteApplication->dispatch() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:233 0.1231 4075400 5. Joomla\CMS\Component\ComponentHelper::renderComponent() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:194 0.1240 4093112 6. Joomla\CMS\Component\ComponentHelper::executeComponent() /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:356 0.1242 4124144 7. require_once('/var/www/astarmathsandphysics/components/com_content/content.php') /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:381 0.1252 4146864 8. ContentController->execute() /var/www/astarmathsandphysics/components/com_content/content.php:42 0.1252 4146864 9. ContentController->display() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:710 0.1898 4771352 10. ContentController->display() /var/www/astarmathsandphysics/components/com_content/controller.php:113 0.1926 4872336 11. Joomla\CMS\Cache\Controller\ViewController->get() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:663 0.1931 4893264 12. ContentViewArticle->display() /var/www/astarmathsandphysics/libraries/src/Cache/Controller/ViewController.php:102 0.2031 4959408 13. Joomla\CMS\Plugin\PluginHelper::importPlugin() /var/www/astarmathsandphysics/components/com_content/views/article/view.html.php:189 0.2031 4959664 14. Joomla\CMS\Plugin\PluginHelper::import() /var/www/astarmathsandphysics/libraries/src/Plugin/PluginHelper.php:182 Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; JCommentsACL has a deprecated constructor in /var/www/astarmathsandphysics/components/com_jcomments/classes/acl.php on line 17 Call Stack: 0.0001 361936 1. {main}() /var/www/astarmathsandphysics/index.php:0 0.0482 1210568 2. Joomla\CMS\Application\SiteApplication->execute() /var/www/astarmathsandphysics/index.php:49 0.0482 1210568 3. Joomla\CMS\Application\SiteApplication->doExecute() /var/www/astarmathsandphysics/libraries/src/Application/CMSApplication.php:267 0.1218 4047832 4. Joomla\CMS\Application\SiteApplication->dispatch() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:233 0.1231 4075400 5. Joomla\CMS\Component\ComponentHelper::renderComponent() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:194 0.1240 4093112 6. Joomla\CMS\Component\ComponentHelper::executeComponent() /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:356 0.1242 4124144 7. require_once('/var/www/astarmathsandphysics/components/com_content/content.php') /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:381 0.1252 4146864 8. ContentController->execute() /var/www/astarmathsandphysics/components/com_content/content.php:42 0.1252 4146864 9. ContentController->display() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:710 0.1898 4771352 10. ContentController->display() /var/www/astarmathsandphysics/components/com_content/controller.php:113 0.1926 4872336 11. Joomla\CMS\Cache\Controller\ViewController->get() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:663 0.1931 4893264 12. ContentViewArticle->display() /var/www/astarmathsandphysics/libraries/src/Cache/Controller/ViewController.php:102 0.3341 12515208 13. JEventDispatcher->trigger() /var/www/astarmathsandphysics/components/com_content/views/article/view.html.php:199 0.3343 12515608 14. plgContentJComments->update() /var/www/astarmathsandphysics/libraries/joomla/event/dispatcher.php:160 0.3343 12515608 15. plgContentJComments->onContentAfterDisplay() /var/www/astarmathsandphysics/libraries/joomla/event/event.php:70 0.3345 12523856 16. plgContentJComments->onAfterDisplayContent() /var/www/astarmathsandphysics/plugins/content/jcomments/jcomments.php:339 0.3348 12525592 17. JComments::show() /var/www/astarmathsandphysics/plugins/content/jcomments/jcomments.php:282 0.3354 12558640 18. JCommentsFactory::getACL() /var/www/astarmathsandphysics/components/com_jcomments/jcomments.php:188 0.3354 12559040 19. spl_autoload_call() /var/www/astarmathsandphysics/components/com_jcomments/classes/factory.php:274 0.3355 12559120 20. JLoader::load() /var/www/astarmathsandphysics/components/com_jcomments/classes/factory.php:274

Lenz's Law

Lenz's law gives the direction of an induced EMF which induces a current flow. It is always so as to oppose the change causing it. This change may be a magnetic field increasing in magnetic, such as when a a primary coil in a transformer is connected to a voltage supply. An EMF will be induced in the secondary circuit but the polarity will opposite to the EMF in the primary circuit. If the voltage in the primary circuit is kept constant, the voltage in the secondary circuit will fall, because it is a CHANGE in the primary which induces a voltage in the secondary.

If the primary circuit is then disconnected, the voltage across the primary wires will fall, but the secondary coil will oppose this fall. An EMF will be induced in the secondary circuit to oppose this fall of voltage in the primary circuit. The voltage in the secondary coil will fall to zero if the primary circuit is kept disconnected.

Lenz's law is applicable to a wide variety of situations. A magnet stationary relative to a current loop will induce no current but if it moves towards the loop a current will be induced. This current will also be associated with a magnetic field, the direction of which is given by the right hand rule. The magnetic field will be in the opposite direction to the current of the moving magnet that induced the current (above center). The magnetic fields will repel each other.

If as above right, the direction of motion of the magnet is reversed, so is the EMF induced in the wire. The effect is to oppose the motion of the magnet is being withdrawn from the vicinity of the wire, so the force is attractive.

Add comment

Security code
Refresh