Answer: Option D. -> positive
:
D

Electric cell is a device which converts chemical energy into electrical energy. All electric cells have two terminals. Metal cap on an electric cell is considered as the positive terminal of the cell whereas metal disc of an electric cell is considered as the negative terminal of the cell.

Answer: Option B. -> Bulb would not glow.
:
B

The bulb will glow only when the circuit is complete. Here, one of the terminals of the battery was disconnected. So, the circuit is not complete and the bulb will not glow. 

Answer: Option B. -> False
:
B

Electric current is a flow of charges. Electricity passes through a material when there are free electrons present in them. Materials that don't conduct electricity (with very few free electrons or even no free electrons) are called insulators. Rubber is an insulator as electrons are tightly held so that no electrons are free to move.

Answer: Option A. -> True
:
A

Electric current can only flow when there is a closed path. The flow of electrons through the filament of a bulb generates heat and light. Hence, an electric bulb glows only when the circuit is closed.

Answer: Option A. -> No current flows through the circuit.
:
A
A switch is a device that is used to make or break an electric circuit. When the switch is turned off, it breaks the circuit and no current flows. When you turn on the switch, the circuit gets complete and the current starts to flow.

Answer: Option B. -> A switch is used to make or break a circuit.
:
B
A switch is an electrical component that can make or break an electrical circuit. When the switch is 'ON', the circuit is closed, providing a path for the electric current to flow. On the other hand, when the switch is 'OFF', the circuit is open, thereby breaking the path of the flow of current.

Answer: Option A. -> Bulb's filament is broken.
:
A
If an electric bulb does not glow even when it is connected to the cell, it could be due to one of the following reasons:
1. The bulb is fused. The part of a bulb that completes the circuit is its filament. A bulb that has a broken filament is termed as a 'fused bulb'.
2. Circuit may be broken. This may be because switch is off, a blown fuse, burnt wires, etc.
3. Connecting wires are made of an insulator. Usually copper, being a good conductor, is used to make connecting wires.
So, the circuit was not complete and hence the bulb did not glow.

Answer: Option A. -> True
:
A
Materials which allow electric current to pass through them are called conductors. Materials used for making wires should always be good conductors. Copper is the frequently used material in making of wires.

Answer: Option A. -> True
:
A
The two terminals of the battery should not be connected to each other without connecting it through a bulb or switch because the chemicals in the cell gets used up very fast and the cell stops working in a short period of time.

Answer: Option A. -> copper
:
A

Switches are devices used to make or break the electric circuit.  Sockets are devices which allows the electric equipment to get connected to the power sources. Electric plugs are present in the electric equipments such that it can be connected to the sockets to complete the circuit. Internal parts of switches, electrical plugs, and sockets are made up of conductors, such as copper, to allow electricity to pass through them.