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 362392 1. {main}() /var/www/astarmathsandphysics/index.php:0 0.0674 1211736 2. Joomla\CMS\Application\SiteApplication->execute() /var/www/astarmathsandphysics/index.php:49 0.0674 1211736 3. Joomla\CMS\Application\SiteApplication->doExecute() /var/www/astarmathsandphysics/libraries/src/Application/CMSApplication.php:267 0.1357 4192824 4. Joomla\CMS\Application\SiteApplication->dispatch() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:233 0.1370 4220368 5. Joomla\CMS\Component\ComponentHelper::renderComponent() /var/www/astarmathsandphysics/libraries/src/Application/SiteApplication.php:194 0.1377 4238080 6. Joomla\CMS\Component\ComponentHelper::executeComponent() /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:356 0.1379 4268600 7. require_once('/var/www/astarmathsandphysics/components/com_content/content.php') /var/www/astarmathsandphysics/libraries/src/Component/ComponentHelper.php:381 0.1389 4291320 8. ContentController->execute() /var/www/astarmathsandphysics/components/com_content/content.php:42 0.1389 4291320 9. ContentController->display() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:710 0.1841 4962720 10. ContentController->display() /var/www/astarmathsandphysics/components/com_content/controller.php:113 0.1876 5154872 11. Joomla\CMS\Cache\Controller\ViewController->get() /var/www/astarmathsandphysics/libraries/src/MVC/Controller/BaseController.php:663 0.1881 5175800 12. ContentViewArticle->display() /var/www/astarmathsandphysics/libraries/src/Cache/Controller/ViewController.php:102 0.1989 5370464 13. Joomla\CMS\Plugin\PluginHelper::importPlugin() /var/www/astarmathsandphysics/components/com_content/views/article/view.html.php:189 0.1990 5370720 14. Joomla\CMS\Plugin\PluginHelper::import() /var/www/astarmathsandphysics/libraries/src/Plugin/PluginHelper.php:182

The Telescope

A telescope in normal adjustment is shown above. The objective and eyepiece lenses are separated by a distance equal to the sum of the focal lengths.

An object at infinity – a star or planet forms an image at the focal point of the objective lens. The image so formed becomes the object for the eyepiece lens, which then forms an image at infinity. The angular magnification is given by

The image so formed is inverted, virtual and larger than the original object.

Thenumber of a telescope is given by the ratiowhere D is the diameter of the objective lens. We can increase the magnification by increasing the ratioWe can either increase the focal length of the objective, which also implies increasing the diameterof the objective so that the f number is not too large. A largenumber means a dim image. The magnification is usually increased by changing the eyepiece for one of a smaller focal length and adjusting the separation between the lenses.