Exercise

A horizontal wire carries a current as shown in the figure below between magnetic poles N and S:

The direction of the force on the wire due to the magnet is:

In an electric motor, the direction of current in the coil changes once in each:

A current that always flows through an electric device in the same direction is called  direct current or $\mathrm{DC}$. The polarity (positive and negative) of a direct current is fixed.

A current that reverses direction at equal intervals of time is called the alternating current or $\mathrm{AC}$. The polarity (positive and negative) of an alternating current is not fixed.

Both $\mathrm{DC}$ and $\mathrm{AC}$ can be used for lighting and heating. Some electric devices like the television need $\mathrm{DC}$ to operate. In such cases, an adapter or a device is fitted into them to convert $\mathrm{AC}$ from the mains supply to $\mathrm{DC}$.

On the basis of above information, answer the following:

The household supply that we get reverses its direction every

A current that always flows through an electric device in the same direction is called  direct current or $\mathrm{DC}$. The polarity (positive and negative) of a direct current is fixed.

A current that reverses direction at equal intervals of time is called the alternating current or $\mathrm{AC}$. The polarity (positive and negative) of an alternating current is not fixed.

Both $\mathrm{DC}$ and $\mathrm{AC}$ can be used for lighting and heating. Some electric devices like the television need $\mathrm{DC}$ to operate. In such cases, an adapter or a device is fitted into them to convert $\mathrm{AC}$ from the mains supply to $\mathrm{DC}$.

On the basis of above information, answer the following:

For long distance transmission of electricity, which one is generally preferred?

The maximum number of $40 \mathrm{W}$ tube-lights connected in parallel which can safely be run from a $240 \mathrm{V}$ supply with a $5 \mathrm{A}$ fuse is:

A TV set consumes an electric power of $230 \mathrm{watts}$ and runs on $230 \mathrm{volts}$ mains supply. The correct fuse for this TV set is:

A charged particle enters at right angles into a uniform magnetic field as shown:

What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to its interaction with the magnetic field?

What is the main purpose of earthing an electrical appliance?