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Which of the following describes the definition of yield strength (σy)?
The NCERT states, 'The point B in the curve is known as yield point (also known as elastic limit) and the corresponding stress is known as yield strength (σy) of the material.' This implies that exceeding this stress leads to permanent deformation.
A material undergoing 'plastic deformation' means:
According to the NCERT, 'When the load is removed, say at some point C between B and D, the body does not regain its original dimension. In this case, even when the stress is zero, the strain is not zero. The material is said to have a permanent set. The deformation is said to be plastic deformation.'
Which point on the stress-strain curve indicates the complete failure of the material?
The NCERT states, 'Beyond this point [D], additional strain is produced even by a reduced applied force and fracture occurs at point E.' Fracture signifies the complete failure of the material.
The stress-strain curves vary from material to material. What do these curves primarily help us understand?
The NCERT highlights, 'The stress-strain curves vary from material to material. These curves help us to understand how a given material deforms with increasing loads.'
What is the nature of the deformation in the O to A region of a stress-strain curve?
The NCERT states, 'In the region between O to A, ... The body regains its original dimensions when the applied force is removed. In this region, the solid behaves as an elastic body.' Elastic implies reversible.
Which of the following physicists proposed the hypothesis that material particles also have a dual (wave-like) nature, providing an explanation for Bohr's second postulate?
The text states: 'The French physicist Louis de Broglie explained this puzzle in 1923, ten years after Bohr proposed his model.' and 'We studied, in Chapter 11, about the de Broglie’s hypothesis that material particles, such as electrons, also have a wave nature.'
Bohr's second postulate of quantization states that the angular momentum of an electron orbiting the nucleus is quantised. Which of the following expressions correctly represents this postulate?
The context explicitly states: '(that is, $L_n = nh/2\pi$; n = 1, 2, 3 …).'
In de Broglie's explanation of Bohr's quantization, the electron in its circular orbit is viewed as a:
The context says: 'Louis de Broglie argued that the electron in its circular orbit, as proposed by Bohr, must be seen as a particle wave.'
According to de Broglie's hypothesis, for an electron to reside in a stable orbit, the circumference of the orbit must be equal to what, in terms of its de Broglie wavelength ($\lambda$)?
The text states: 'De Broglie’s hypothesis...gave an explanation for Bohr’s quantised orbits by bringing in the wave-particle duality. The orbits correspond to circular standing waves in which the circumference of the orbit equals a whole number of wavelengths.' This is mathematically represented as $2\pi r_n = n\lambda$.
Which of the following scientists experimentally verified the wave nature of electrons?
The context mentions: 'C. J. Davisson and L. H. Germer later experimentally verified the wave nature of electrons in 1927.'
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.