When a charge of $3\, C$ is placed in a uniform electric field,it experiences a force of $3000\, N$. Within this field,the potential difference between two points separated by a distance of $1\, cm$ is:

Two concentric coils of $10$ turns each are placed in the same plane. Their radii are $20 \ cm$ and $40 \ cm$ and carry $0.2 \ A$ and $0.3 \ A$ current respectively in opposite directions. The magnetic induction (in $T$) at the centre is

Which of the following is not correctly matched?

The colour sequence in a carbon resistor is red,brown,orange,and silver. The resistance of the resistor is:

During the electrolytic reduction of alumina,the reaction at cathode is

Protein can be most easily removed from which of the following?