어과수
2023-03-31 15:16
소리나 지진파 등은 공기나 물 등의 매질이 있어야 이동할 수 있어요.
그런데 빛이나 전파 등의 전자기파는 매질이 없어도 됩니다.
전기장과 자기장이 서로를 이끌어나가기 때문이라고 하는데요, 그 원리가 뭔지 영상으로 확인해 보세요.
Severity: Notice
Message: Undefined variable: total
Filename: templates/commentlist.php
Line Number: 8
Backtrace:
File: /var/www/html_dev/mkids_dongascience_com/application/views/templates/commentlist.php Line: 8 Function: _error_handler
File: /var/www/html_dev/mkids_dongascience_com/application/views/kids_tv/viewContents.php Line: 82 Function: view
File: /var/www/html_dev/mkids_dongascience_com/application/controllers/Kids_tv.php Line: 128 Function: view
File: /var/www/html_dev/mkids_dongascience_com/www/index.php Line: 301 Function: require_once
A PHP Error was encountered
Severity: Notice
Message: Undefined variable: total
Filename: templates/commentlist.php
Line Number: 8
Backtrace:
File: /var/www/html_dev/mkids_dongascience_com/application/views/templates/commentlist.php
Line: 8
Function: _error_handler
File: /var/www/html_dev/mkids_dongascience_com/application/views/kids_tv/viewContents.php
Line: 82
Function: view
File: /var/www/html_dev/mkids_dongascience_com/application/controllers/Kids_tv.php
Line: 128
Function: view
File: /var/www/html_dev/mkids_dongascience_com/www/index.php
Line: 301
Function: require_once