What is current electricity? Define closed and open circuits with the neat figures of each.

The flow of electrons in a definite direction is called current electricity.

i. Open electric circuit:
An electric circuit in which no current is flowing is called an open circuit.

ii. Closed electric circuit:
An electro circuit in which electric current is flowing continuously is called a closed electric circuit.

Why is a thin long tungsten wire used in an electric bulb?

A thin and long tungsten wire is used in an electric bulb because it has very high resistivity and has a very high melting point. So, it doesn't melt even if the light bulb has a high temperature.

What is a dynamo? Draw a well-labeled diagram of an electromagnet.

The device which converts mechanical energy into electrical energy is called a dynamo.

Draw a neat diagram showing an electric bell.

fig. Electric bell

An electric bulb should be filled with inert gas.

We know, inert gas doesn't take part in any reaction due to its stable state of electronic configuration. As a result, using its property, to avoid chemical reaction inside bulb even in extreme temperature inert gas is used to fill the electric bulb.

The angle of dip in the magnetic south pole of the earth is 90 degree. Give reason

The angle of dip in the magnetic south pole of the earth is 90 degree because the needle remains vertically at the poles.

Ammeter is connected in series and voltmeter is connected parallel in an electric circuit, why?

Ammeter is the device used to measure the electric current. So, total current flowing through the circuit must pass through the ammeter. Therefore, it is connected in series. While voltmeter is the device used to measure the potential difference between two ends. Therefore, voltmeter is parallel to measure the potential difference across two ends.

Germanium and silicon are also known as semiconductor, why? Give reason

Define series combination and parallel combination of cells. In which condition are cells connected in series?