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Why are electrons not found confined within the nucleus?

1. Because the de-Broglie wavelength of an electron emitted in β-decay is much smaller than the nuclear size
2. Because the de-Broglie wavelength of an electron emitted in β-decay is much larger than the nuclear size
3. Because the de-Broglie wavelength of an electron emitted in β-decay is comparable to the size of the nucleus
4. Because a negative charge cannot be present inside the nucleus

Correct answer: Because the de-Broglie wavelength of an electron emitted in β-decay is much larger than the nuclear size

Solution

An electron confined to nuclear dimensions would, by the uncertainty principle, need enormous energy; equivalently the de-Broglie wavelength of a beta-decay electron is far larger than the nucleus (~10^-14 m), so electrons cannot be bound inside the nucleus.

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