A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. The flow of electrons provides an electric current that can be used to do work.
Your task is to generate electricity through a chemical reaction. Which among the following groups would you use?
Important Questions on Chemical Effects of Electric Current
A coil is wrapped loosely around a cylindrical wooden piece and its ends are connected to a battery as shown. In which case will the compass needle placed near the coil deflect when the circuit is closed?
Given below is a diagrammatic representation of an electromagnet. The strength of the magnetic field between the poles of the electromagnet would be UNCHANGED if the
The figure shows a person holding a polythene strip after it has been rubbed with a duster cloth. The strip acquires a negative charge. Yet, after a few seconds, the duster cloth does not show any charge. Which of the following could be the reason for this?
The following experiment was conducted in the physics laboratory. A wooden pencil is sharpened at both ends. It is connected to two bulbs and a battery as shown. The two crocodile clips are connected to the wooden part of the pencil.
Students noticed that the bulbs do not light up. Why do the two bulbs not light up?
Akhil and friends have made the following circuit. Two crocodile clips are connected to the lead or graphite of the pencil as shown. The two bulbs connected to the circuit will light up dimly. Why do the two bulbs light up?
A conductor is a material that allows electricity to flow through it. An Insulator is a material that electricity cannot flow through.
To determine whether an object is a conductor or insulator, you can build a simple circuit with a battery, light bulb, and three pieces of wire.
Touch the free ends of the wire to the object you are testing. If the light bulb lights up, the object is made from a conductor. If it does not, the object is made from an insulator.
| Object | Conductor / Insulator |
| Rubber band | |
| Penny | |
| Nickel | |
| Tooth pick | |
| Key | |
| Paper clip | |
| Brass paper fastener | |
| Glass microscope slide |
We can easily draw electrical circuits by following some simple rules.
1. Use a ruler to draw straight lines to represent the wires.
2. Use the correct circuit symbols to represent different components.
3. Ensure that the circuit is closed and has no gaps.
Write down as many things as possible that is wrong with the circuit below?
Sulphur is an electrical insulator, but it can be made to conduct electricity if a very bright light shines on it. A very bright light shines onto a small circular area in the centre of the charged slab of sulphur. The pattern of charge on the sulphur alters. The simplified diagram represents the new pattern of charge.
Explain why the pattern alters in this way.
