I watched a video on youtube and I got some info about meters. In the video it was explained that in duple meter (2/4) the first beat is strong(accented) and the second beat is weak in a measure and in 4/4 meter the first beat is strong, 3rd is a medium beat and 4th and 2nd are weak. So when we are playing piano in duple meter, do we have to play notes louder on strong beats and normal on weak beats or do I have to know more about this, I know I might be sounding stupid here but I have just started learning music theory Any links to valuable articles related to this topic would be great. Don't mind my bad English.
To get a sort of rhythm going, you need loud(er) and quiet(er) notes in your tunes. This is dictated by the time signature. In 2/4 time, beat 1 is louder than beat two. In 4/4 time, beat 1 is loudest (like always), 2 and 4 are less so, but 3 is quieter than 1, but louder than 2 and 4. Listen to a lot of songs and you can feel and hear that, although it's often quite a subtle difference, with some songs changing the feel by moving the emphasis off those beats,so it's not as straightforward as it seems.
As has been said so many times before - the theory tries to explain what happens, but it isn't a set of rules that we have to follow. So do not have the idea that learning theory will make music easier - necessarily.
You don't need to over-think this. Sing a march to yourself. "be Kind to your Web-footed Friends .... for a Duck may be Some-body's Mo- Ther..." (The Stars and Stripes Forever, capiche?) The capital letters are the 'One' counts. The places in the music that get the left foot when marching. That's how much accent you have to give to ONE, two, ONE, two in a 2/4 piece. It isn't forced. It's really just 'how the music goes'.