P5 Quiz

Jackie rubs a balloon against Sam's hair. The hair sticks to the balloon. When Jackie removes the balloon, Sams hair stands on end for a few minutes, then slowly falls back down again. Explain what happens to each object.

The balloon and the hair are ❌. When the balloon is ❌ against the hair, ❌ are transferred from the balloon to the hair, meaning the balloon is ❌ charged and the hair is ❌ charged. The hair sticks to the balloon as the objects are ❌ charged and opposite charges ❌. As the strands of hair have the ❌ charge they ❌, causing them to stand on end. The hair slowly begins to fall back down again as the strands of hair begin to be ❌.

In an electrical ❌, all the components have charges that are ❌ to move. When a circuit is made, the cell (❌) causes these free charges to move. They move in a ❌ loop around the circuit, transferring electrical energy into light and ❌ at the bulb. The electrons carry a ❌ charge, so will flow from the negative ❌ of the cell towards the ❌ terminal.
The strength of an electric current is measured in ❌, usually shortened to amps. Amps are a measure of how much electric charge is flowing round the circuit per ❌.

The size of a ❌ in a circuit depends on the ❌ of the battery and the resistance of the ❌ in the circuit.
Voltage can be thought of as the '❌' it exerts on charges in the circuit. A ❌ voltage means a bigger 'push', resulting in a ❌ current. The scientific term for voltage is potential ❌. It refers to the difference in ❌ per unit charge.
An electric current flows when charged ❌ called electrons move through a ❌. The moving electrons can collide with the ❌ of the conductor. This is called resistance and it makes it ❌ for current to flow. These collisions make the conductor ❌. It is this that makes a lamp filament hot enough to ❌.

When ❌ are connected in ❌, their total resistance is the sum of their individual resistances. For example, if a 2 Ω resistor, a 1 Ω resistor and a 3 Ω resistor are connected side by side, their total resistance is 2 + 1 + 3 = ❌ Ω.
If you ❌ the number of lamps in a series circuit, the total ❌ will increase and less current will flow. The resistance in a circuit can also be altered using ❌ resistors. For example, these components may be used in dimmer switches, or to control the volume of a CD player.

A ❌ is produced when a magnet is moving into a coil of wire. This process is called electromagnetic ❌. The direction of the induced voltage is ❌ when the magnet is moved out of the coil again. It can also be reversed if the other pole of the magnet is moved into the ❌. If the coil is part of a ❌ circuit then a current will be induced in the circuit.
It is not practical to ❌ large amounts of electricity by passing a magnet in and out of a coil of wire. Instead, generators induce a current by ❌ a coil of wire inside a magnetic field, or by spinning a ❌ inside a coil of wire. As this happens, a ❌ difference is produced between the ends of the coil, which causes a ❌ to flow. When a wire is moved in the magnetic field of a ❌, the movement, magnetic field and current are all at right angles to each other. If the wire is moved in the ❌ direction, the induced current also moves in the opposite direction.
Remember that one side of a coil in a generator moves ❌ during one half turn, and then down during the next half turn.
This means that as a coil is rotated in a magnetic field, the induced current ❌ direction every ❌. This is called ❌ current (AC).

Why do power stations use generators that produce ❌ current?
As it is ❌ to use transformers to increase the voltage of electricity before it is transported using the ❌ grid. The ❌ in power lines is kept very high an the current very ❌ to reduce the amount of ❌ energy. If a high current was passing through the ❌ cables (which have high ❌) lots of energy would be transferred to ❌ energy as there would be lots of collisions. By keeping the current low, we ❌ heat loss and wasted energy.