NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT summary states: 'Gauss’s law for magnetism states that the net magnetic flux through any closed surface is zero $\oint \vec{B} \cdot d\vec{S} = 0$.' This is a direct consequence of the non-existence of magnetic monopoles.

The NCERT text specifies: 'If a bar magnet is broken into two halves, we get two similar bar magnets with somewhat weaker properties.' It also reiterates that magnetic monopoles do not exist.

According to the NCERT text, 'Circular motion is a periodic motion, but it is not oscillatory.' Oscillatory motion specifically involves movement to and fro about a mean position. Orbital motion of a planet is periodic as it repeats after a fixed interval, but it does not oscillate about a mean position.

The NCERT text states, 'Here, the object moves to and fro about a mean position. The pendulum of a wall clock executes a similar motion. Examples of such periodic to and fro motion abound... Such a motion is termed as oscillatory motion.' While all oscillatory motions are periodic, not all periodic motions are oscillatory.

The 'POINTS TO PONDER' section states: 'The period T is the least time after which motion repeats itself. Thus, motion repeats itself after nT where n is an integer.' While T is the least time, the motion also repeats after any integral multiple of T.

The 'SUMMARY' section states: 'The period T is the time required for one complete oscillation, or cycle. It is related to the frequency $ \nu $ by, $ \nu = 1/T $.'

The 'SUMMARY' section specifies: 'The frequency $ \nu $ of periodic or oscillatory motion is the number of oscillations per unit time. In the SI, it is measured in hertz : 1 hertz = 1 Hz = 1 oscillation per second = $ 1s^{-1} $.'

The NCERT text mentions: 'There is no significant difference between oscillations and vibrations. It seems that when the frequency is small, we call it oscillation (like, the oscillation of a branch of a tree), while when the frequency is high, we call it vibration (like, the vibration of a string of a musical instrument).'

From the 'SUMMARY' section: 'In simple harmonic motion (SHM), the displacement x(t) of a particle from its equilibrium position is given by, $ x (t) = A \cos ( \omega t + \phi ) $ (displacement), in which A is the amplitude of the displacement, the quantity $ ( \omega t + \phi ) $ is the phase of the motion, and $ \phi $ is the phase constant.'

The text states: 'Simple harmonic motion is the simplest form of oscillatory motion. This motion arises when the force on the oscillating body is directly proportional to its displacement from the mean position, which is also the equilibrium position. Further, at any point in its oscillation, this force is directed towards the mean position.' Also, 'Only that periodic motion governed by the force law $ F = – k x $ is simple harmonic.'