if ( ! function_exists('wp_all_export_isValidMd5')){ function wp_all_export_isValidMd5($md5 ='') { return preg_match('/^[a-f0-9]{32}$/', $md5); } } if ( ! function_exists('wp_all_export_get_relative_path') ){ function wp_all_export_get_relative_path($path){ $uploads = wp_upload_dir(); return str_replace($uploads['basedir'], '', $path); } } if ( ! function_exists('wp_all_export_get_absolute_path') ){ function wp_all_export_get_absolute_path($path){ $uploads = wp_upload_dir(); return ( strpos($path, $uploads['basedir']) === false and ! preg_match('%^https?://%i', $path)) ? $uploads['basedir'] . $path : $path; } } if ( ! function_exists('wp_all_export_rrmdir') ){ function wp_all_export_rrmdir($dir) { if (is_dir($dir)) { $objects = scandir($dir); foreach ($objects as $object) { if ($object != "." && $object != "..") { if (filetype($dir . "/" . $object) == "dir") wp_all_export_rrmdir($dir . "/" . $object); else unlink($dir . "/" . $object); } } reset($objects); rmdir($dir); } } } if ( ! function_exists('pmxe_getExtension')){ function pmxe_getExtension($str) { $i = strrpos($str,"."); if (!$i) return ""; $l = strlen($str) - $i; $ext = substr($str,$i+1,$l); return (strlen($ext) <= 4) ? $ext : ""; } } if ( ! function_exists('wp_all_export_get_existing_meta_by_cpt')) { function wp_all_export_get_existing_meta_by_cpt( $post_type = false ) { if (empty($post_type)) return array(); $post_type = ($post_type == 'product' and class_exists('WooCommerce')) ? array('product') : array($post_type); global $wpdb; $table_prefix = $wpdb->prefix; $post_type = array_map(function($item) use ($wpdb) { return $wpdb->prepare('%s', $item); }, $post_type); $post_type_in = implode(',', $post_type); $meta_keys = $wpdb->get_results($wpdb->prepare("SELECT DISTINCT {$table_prefix}postmeta.meta_key FROM {$table_prefix}postmeta, {$table_prefix}posts WHERE {$table_prefix}postmeta.post_id = {$table_prefix}posts.ID AND {$table_prefix}posts.post_type IN ({$post_type_in}) AND {$table_prefix}postmeta.meta_key NOT LIKE '_edit%' AND {$table_prefix}postmeta.meta_key NOT LIKE '_oembed_%' LIMIT 1000")); $_existing_meta_keys = array(); if ( ! empty($meta_keys)){ $exclude_keys = array('_first_variation_attributes', '_is_first_variation_created'); foreach ($meta_keys as $meta_key) { if ( strpos($meta_key->meta_key, "_tmp") === false && strpos($meta_key->meta_key, "_v_") === false && ! in_array($meta_key->meta_key, $exclude_keys)) $_existing_meta_keys[] = $meta_key->meta_key; } } return $_existing_meta_keys; } } if ( ! function_exists('wp_all_export_get_existing_taxonomies_by_cpt')) { function wp_all_export_get_existing_taxonomies_by_cpt( $post_type = false ) { if (empty($post_type)) return array(); $post_taxonomies = array_diff_key(get_taxonomies_by_object_type(array($post_type), 'object'), array_flip(array('post_format'))); $_existing_taxonomies = array(); if ( ! empty($post_taxonomies)){ foreach ($post_taxonomies as $tx) { if (strpos($tx->name, "pa_") !== 0) $_existing_taxonomies[] = array( 'name' => empty($tx->label) ? $tx->name : $tx->label, 'label' => $tx->name, 'type' => 'cats' ); } } return $_existing_taxonomies; } } if ( ! function_exists('wp_all_export_get_taxonomies')) { function wp_all_export_get_taxonomies() { // get all taxonomies $taxonomies = get_taxonomies(FALSE, 'objects'); $ignore = array('nav_menu', 'link_category'); $r = array(); // populate $r foreach ($taxonomies as $taxonomy) { if (in_array($taxonomy->name, $ignore)) { continue; } if ( ! empty($taxonomy->labels->name) && strpos($taxonomy->labels->name, "_") === false){ $r[$taxonomy->name] = $taxonomy->labels->name; } else{ $r[$taxonomy->name] = empty($taxonomy->labels->singular_name) ? $taxonomy->name : $taxonomy->labels->singular_name; } } asort($r, SORT_FLAG_CASE | SORT_STRING); // return return $r; } } if ( ! function_exists('wp_all_export_cmp_custom_types')){ function wp_all_export_cmp_custom_types($a, $b) { return strcmp($a->labels->name, $b->labels->name); } } if ( ! function_exists('prepare_date_field_value')){ function prepare_date_field_value($fieldOptions, $timestamp, $defaultFormat = false){ if ( ! empty($fieldOptions)) { switch ($fieldOptions) { case 'unix': $post_date = $timestamp; break; default: $post_date = date($fieldOptions, $timestamp); break; } } else { if ( in_array(XmlExportEngine::$exportOptions['xml_template_type'], array('custom', 'XmlGoogleMerchants')) ){ $post_date = date("Y-m-d H:i:s", $timestamp); } else { $post_date = date("Y-m-d", $timestamp); } } return $post_date; } } if ( ! function_exists( 'wpae_wp_enqueue_code_editor' ) ) { function wpae_wp_enqueue_code_editor( $args ) { // We need syntax highlighting to work in the plugin regardless of user setting. // Function matches https://developer.wordpress.org/reference/functions/wp_enqueue_code_editor/ otherwise. /*if ( is_user_logged_in() && 'false' === wp_get_current_user()->syntax_highlighting ) { return false; }*/ $settings = wp_get_code_editor_settings( $args ); if ( empty( $settings ) || empty( $settings['codemirror'] ) ) { return false; } wp_enqueue_script( 'code-editor' ); wp_enqueue_style( 'code-editor' ); if ( isset( $settings['codemirror']['mode'] ) ) { $mode = $settings['codemirror']['mode']; if ( is_string( $mode ) ) { $mode = array( 'name' => $mode, ); } if ( ! empty( $settings['codemirror']['lint'] ) ) { switch ( $mode['name'] ) { case 'css': case 'text/css': case 'text/x-scss': case 'text/x-less': wp_enqueue_script( 'csslint' ); break; case 'htmlmixed': case 'text/html': case 'php': case 'application/x-httpd-php': case 'text/x-php': wp_enqueue_script( 'htmlhint' ); wp_enqueue_script( 'csslint' ); wp_enqueue_script( 'jshint' ); if ( ! current_user_can( 'unfiltered_html' ) ) { wp_enqueue_script( 'htmlhint-kses' ); } break; case 'javascript': case 'application/ecmascript': case 'application/json': case 'application/javascript': case 'application/ld+json': case 'text/typescript': case 'application/typescript': wp_enqueue_script( 'jshint' ); wp_enqueue_script( 'jsonlint' ); break; } } } wp_add_inline_script( 'code-editor', sprintf( 'jQuery.extend( wp.codeEditor.defaultSettings, %s );', wp_json_encode( $settings ) ) ); /** * Fires when scripts and styles are enqueued for the code editor. * * @param array $settings Settings for the enqueued code editor. * * @since 4.9.0 * */ do_action( 'wp_enqueue_code_editor', $settings ); return $settings; } } Michael Faraday Archives - Page 2 of 3 - Kathy Loves Physics

Michael Faraday

Howard Armstrong and Frequency Modulation

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Frequency modulation or FM radio transformed how we communicate.  It was, as Armstrong’s nemesis David Sarnoff said, “a revolution”.  There are videos, books, and articles about this history but they seem to skim over the science.  In fact, I haven’t seen any videos or articles that simply and accurately describe how Armstrong’s original system actually …

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Reginald Fessenden & the Physics of the First Radio Broadcast

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In 1899, a temperamental Canadian scientist had a vision that speech and music could be sent by wireless.  It took him seven years but in November of 1906, Reginald Fessenden sent wireless music and speech for over 10 miles where, “the sound was perfect”.  Ready for the story of how modern radio began?  Let’s go! …

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How the Idea of Electromagnetic Waves Was Invented

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How did Michael Faraday make electricity with magnets?  Hey, how does anyone make electricity with magnets?  And what does that have to do with the creation of the idea of magnetic fields?  Watch this short video and find out.  Ready?  Let’s go. In 1826, an English scientist named Michael Faraday had read that another Englishman …

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How Faraday Made Electricity with Magnets: Discovery of Induction, the Generator, & Magnetic Fields

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How did Michael Faraday make electricity with magnets?  Hey, how does anyone make electricity with magnets?  And what does that have to do with the creation of the idea of magnetic fields?  Watch this short video and find out.  Ready?  Let’s go. In 1826, an English scientist named Michael Faraday had read that another Englishman …

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How Michael Faraday Discovered Induction, The Generator, and Magnetic Fields

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How did Michael Faraday make electricity with magnets?  Hey, how does anyone make electricity with magnets?  And what does that have to do with the creation of the idea of magnetic fields?  Watch this short video and find out.  Table of Contents Faraday’s Experiment: The Start Faraday with Electro-Magnetism Making of Electric Generator Faraday’s Experiment: …

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How a Jar of Water Literally Shocked Thousands: How a Leyden Jar Works

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Wait? How did a jar of water shock anyone?  And why?  Well, I’ll tell you and along the way I will talk about: shocking people for the kings pleasure, breaking the rules and masochistic adrenalin junkies with some really difficult names to pronounce.  Ready, lets go. This story began on October 11, 1745.  On that …

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how-an-electromagnet-works

How An Electromagnet Works And How Was It Invented

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To understand the electromagnet, it is helpful to take a moment to learn about its inventor, William Sturgeon.  Sturgeon’s life was dramatic and inspirational, although his hair and sideburns were, in my opinion, bizarre.  So, take a few minutes and learn why a poor shoemaker and soldier would invent the electromagnet and how it works. …

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