The colour of $KMnO_4$ is due to

The instantaneous displacement of a simple pendulum oscillator is given by $x = A \cos \left( \omega t + \frac{\pi}{4} \right)$. Its speed will be maximum at time:

Four bodies $P, Q, R$ and $S$ are projected with equal velocities having angles of projection $15^o, 30^o, 45^o$ and $60^o$ with the horizontal respectively. The body having the shortest range is

Select the correct statement from the following.

$A$ ray of light of intensity $I$ is incident on a parallel glass slab at point $A$ as shown in the diagram. It undergoes partial reflection and refraction. At each reflection, $25\%$ of incident energy is reflected. The rays $AB$ and $A'B'$ undergo interference. The ratio of $I_{max}$ and $I_{min}$ is (in $: 1$)

The cell junctions called tight,adhering,and gap junctions are found in