# Physics (P2) - Current Electricity

• Created by: Roma
• Created on: 14-12-13 09:36
What happens when two insulating materials are rubbed togher?
Electrons are rubbed off one material and deposited on the other. Which way the electrons are transferred depends on the material.
1 of 28
What is charging by friction?
When insulating materials have been rubbed together, the material that has gained electrons becomes negatively charged and the one that has lost electrons becomes positively charged.
2 of 28
What do objects attract?
If they have opposite electrical charges. The bigger the distance between the objects, the weaker the forces between them.
3 of 28
Why do objects repel?
If they have the same electrical charge. The bigger the distance between the objects, the weaker the forces between them.
4 of 28
What does a cell do?
Push electrons around a complete circuit. Batteries have two or more cells.
5 of 28
What does a switch do?
Enables the current in a circuit to be switched on or off.
6 of 28
What does an indicator do?
Emit light as a signal when a current is passing through it or as a light source e.g. a bulb.
7 of 28
What does a diode do?
Allows a current through in only one direction.
8 of 28
What does a light emitting diode (LED) do?
Emit light when a current passes through it.
9 of 28
What does an ammeter do?
Measure the electric current. It is placed in series with the component.
10 of 28
What does a fixed resistor do?
Limit the current in a circuit.
11 of 28
What does a variable resistor do?
Allow the current to be varied.
12 of 28
What does a fuse do?
Melt and therefore break the circuit if the current through it is greater than a certain amount.
13 of 28
What does a heater do?
Transfer electrical energy to heat the surroundings.
14 of 28
What does a voltmeter do?
Measure the potential difference (i.e. voltage). It is placed parallel to the component.
15 of 28
What does Ohm's law state?
Current is directly proportional to potential difference across a resistor. Any component which obeys this law is called a ohmic conductor.
16 of 28
What happens to the resistance of a filament bulb if the current increases?
The resistance increases as it increases with temperature.
17 of 28
What is the resistance of a diode in a forward and reverse direction?
The resistance in the forward direction is low and the resistance in the reverse direction is high. Therefore the current is zero.
18 of 28
What happens to the resistance of a light depending resistor (LDR) if the light intensity increases?
Resistance decreases.
19 of 28
What happens to the resistance of a thermistor if the temperature increases?
Resistance decreases.
20 of 28
What is a series circuit?
Where the components are connects one after another. If there is a break anywhere, charge stops flowing. The current through each component is the same as there is not choice of route for the charge.
21 of 28
What does current depend on in a series circuit?
The p.d. of the supply and the resistance of the circuit.
22 of 28
What is the supply in a series circuit?
The p.d. of all components added together, as it is shared between all the components in the circuit.
23 of 28
What is the total resistance in a series circuit.
The resistance of the individual components added together. The bigger the resistance, the bigger it's p.d.
24 of 28
What is a parallel circuit?
Each component is connected across the supply, so if there is a break, charge can still flow in other parts.
25 of 28
What is the p.d. in a parallel circuit?
Each component is connected across the supply p.d., so the p.d. across each component is the same.
26 of 28
What do the junctions in a parallel circuit do?
There are conjunctions in a parallel circuit so the charge can flow through different components. The current through each component depends on the resistance. The bigger the resistance, the smaller the current through it.
27 of 28
What is the current in a parallel circuit?
The total current through the whole circuit is equal to the sum of the currents through the separate components.
28 of 28

## Other cards in this set

### Card 2

#### Front

What is charging by friction?

#### Back

When insulating materials have been rubbed together, the material that has gained electrons becomes negatively charged and the one that has lost electrons becomes positively charged.

### Card 3

#### Front

What do objects attract?

### Card 4

#### Front

Why do objects repel?

### Card 5

#### Front

What does a cell do?