Acetaldehyde cannot give:

The time constant of an inductance coil is $3 \text{ ms}$. When a $90 \Omega$ resistance is joined in series,the time constant becomes $0.5 \text{ ms}$. The inductance and the resistance of the coil are:

The coils of a step-down transformer have $500$ and $5000$ turns. In the primary coil,an $AC$ of $4 \, A$ at $2200 \, V$ is sent. The value of the current and potential difference in the secondary coil will be:

If $A+B+C=270^{\circ}$,then $\cos 2A+\cos 2B+\cos 2C$ is equal to:

Select the correct pair from the following.

$A$ conducting rod $AC$ of length $4l$ is rotated about a point $O$ in a uniform magnetic field $\vec B$ directed into the paper. $AO = l$ and $OC = 3l$. Then: