Check the status of redo log file.

set line 200 pages 200
col member for a35
select g.group#,g.member,l.bytes/1024/1024 "Meg",l.status from v$log l,v$logfile g where l.group# = g.group# order by 1,2;

Add the redo member in existing group
you will add the member in each group then use the add command.

ALTER DATABASE ADD LOGFILE MEMBER 'C:\ORACLE\ORADATA\XE\REDO1.LOG' TO GROUP 1;

Drop the redo member from existing redo group
Drop the redo logfile from existing group with following command but you need to manually remove the physical file from the operating system.

ALTER DATABASE DROP LOGFILE MEMBER 'C:\ORACLE\ORADATA\XE\REDO1.LOG';

For changing Active, Current or Inactive Status of redo log files

-- For changing current status of redo 
Alter system switch logfile;

-- For clear active status of redo
Alter system checkpoint;