Chemistry · Structure Of Atom · NEET
Yes. de Broglie said EVERY object in motion has a wave. A ball, a car, even you while walking, all have a de Broglie wave. The formula lambda = h/(mv) always works. The wave is real, but for big objects it is far too small to notice or measure. So it exists on paper, but we never observe it.
Because the wavelength is unbelievably tiny. In the NCERT example, a ball of mass 0.1 kg moving at 10 m/s has lambda = h/(mv) = 6.626 x 10^-34 / (0.1 x 10) = 6.626 x 10^-34 m. That is about 10^-24 times smaller than an atom. No microscope or instrument can detect a wave this small, so it is never observed.
In lambda = h/(mv), the wavelength is inversely proportional to mass. Big objects have a HUGE mass compared to an electron (a ball is about 10^29 times heavier than an electron). This giant mass in the bottom of the fraction crushes lambda to almost zero. Speed matters a little, but mass is the main reason the wave vanishes for large objects.
An electron has a super tiny mass (9.1 x 10^-31 kg). Put that small mass in lambda = h/(mv) and the wavelength comes out around 10^-10 m (same size as an atom). A wavelength this size CAN be measured, and it was proved when electron beams showed diffraction (a wave effect). So light particles = detectable wave; heavy particles = wave too small to detect.
No, the idea is correct for everything. It just becomes meaningless in practice for big objects because the wavelength is smaller than anything we can measure. NCERT says the wave properties of ordinary objects 'cannot be detected' because of their large masses. The theory holds; only the observation fails.
h = 6.626 x 10^-34 J s is extremely small. It sits on top of the formula lambda = h/(mv). Because h itself is so tiny, even a small mass gives a small wavelength, and a large mass gives an impossibly small one. If h were large, we would see waves everywhere. The smallness of h is why matter waves stay hidden in daily life.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Because lambda = h/(mv) and h is extremely small. A large mass m makes lambda tiny, far below what any instrument can detect, so the wave is never observed even though it exists.
lambda = h/(mv) = 6.626 x 10^-34 / (0.1 x 10) = 6.626 x 10^-34 m. This is far smaller than an atom, so it cannot be detected.
Very light particles like electrons, protons and neutrons. Their tiny mass gives a wavelength around 10^-10 m, which is measurable, shown by electron diffraction.
Mass. Wavelength is inversely proportional to mass, and large objects have enormously bigger mass than electrons, so mass is the main reason the wave is not observed.
Yes, it applies to every moving object. But for macroscopic (large) objects the wavelength is so small that wave behaviour is insignificant and the results match classical mechanics.
