I am a mathematician and not a physicist, so I have a lack of understanding subjects of physics. I would like to ask which physical objects are absolutely invisible by us -I mean which objects are invisible by human eye or any human device that we have or we can create- so we can approach them on...

On measuring voltage across the two terminal of solar panel (made of semiconductor material) ,the Voltage (V) increases with increase in intensity (I) of sunlight in open circuit. But it should be proportional to frequency, according to photo-electric effect. Why it seems like contrary? (How PN ...

We can calculate the centripetal acceleration in circular motion by the equation v^2/r. But how do we calculate the jerk (which is acceleration over time)?