Which of the options describes the phase constant for SHM?

[Salman Ali]

The only thing I know is that phase constant tells how much a signal is shifted along the x-axis. The answer of the question is both option a and b. I am not getting it!

 

[mjc123]

What do you get if you add 2π to a?

 

[sophiecentaur]

. I am not getting it!

It's the same as for any function. You can choose the x,y (or any other axes) to be anywhere and the sums are basically still the same. It's lucky in the case of trig functions that they repeat every cycle but the Origin on the t axis is totally arbitrary. It is often chosen so that the phase is a 'convenient' value and to avoid a random φ turning up everywhere in the calculation.

 

[Salman Ali]

So how option a and b are correct? I am not getting the question? What is he asking? Sorry I am very weak in this topic.

It's the same as for any function. You can choose the x,y (or any other axes) to be anywhere and the sums are basically still the same. It's lucky in the case of trig functions that they repeat every cycle but the Origin on the t axis is totally arbitrary. It is often chosen so that the phase is a 'convenient' value and to avoid a random φ turning up everywhere in the calculation.[/QUOT

 

[sophiecentaur]

So how option a and b are correct?

I can see that you are confused.
As far as I can see, your OP is incomplete or could at least have been expanded to help you. The 'phase constant' is a constant that's included in the mathematical (trig) function that is used to describe an SHM waveform. It would be inserted into the sin(ωt) or cos(ωt) depending on which you have chosen for the diagram you posted. The answers will be π/2 different, depending which you choose. I think this is what the question is getting at.
I would recommend that you look at some other example of where the 'phase constant' is used and try to get familiar what it really means, rather than to struggle with this strangely worded question (you may have only shown us part of the question??). The published answers are not always correct so you can never be sure about just one example. (Which is bad for self confidence, of course.)
Consider
V = V₀sin(ωt+φ), which has a zero crossing at t=0
If φ is a small positive value, it means the zero crossing will come early - before t=0. So the phase constant would be small and negative. From what you say, you seem to realize that. But if you use
V=V₀cos(ωt+φ), then the peak (cos(0)) is very late so φ will be around π in that diagram.