electricity Flashcards
- Describe what is meant by a complete circuit.
A complete circuit starts at one end of a power supply and continues to the other end with no gaps.
- Define series and parallel circuits.
Series circuits only have one route.
Parallel circuits have more than one branch.
- State the basic properties of series circuits:
What happens when more bulbs are added?
What happens when one bulb breaks?
As more bulbs are added, existing bulbs get dimmer.
(If the bulbs are identical they will have the same brightness as each other.)
If one bulb breaks, the rest go out.
- State the basic properties of parallel circuits:
What happens when more bulbs are added?
What happens when one bulb breaks?
As more bulbs are added, there is no change in the brightness of existing bulbs.
(If the bulbs are identical they will have the same brightness as each other.)
If one bulb breaks, the rest are unaffected.
- Draw the circuit symbols for a battery, cell, switch, lamp, voltmeter, ammeter and resistor.
Draw on whiteboard and check your answer
- What are the rules for drawing neat circuit diagrams?
Neat circuit diagrams should be drawn with a pencil and a ruler, making sure the symbols are correct and that there are no gaps. The wires are drawn as straight lines with right angles. Symbols are not placed in corners. e.g.
- Define what a conductor is and give 2 examples.
A conductor is a material which allows electricity to flow
e.g. copper, iron
- Define what an insulator is and give 2 examples.
An insulator is a material which does not allow electricity to flow
e.g. rubber, glass.
- Describe what electrical current is.
Electrical current is a flow of charge.
Usually the charges are electrons, which flow away from the negative end of a battery and towards the positive.
How are Ammeters and Voltmeters connected in circuit diagrams?
An ammeter (to measure current) is always added in series and a voltmeter (to measure voltage) in parallel.
- State the rule for current in series circuits.
In a series circuit the current is the same at all positions.
9.&10. Example
A 5.5V battery is connected across 2 bulbs in series.
Bulb 1 has a voltage of 2V. What is the voltage across bulb 2?
The current through bulb 1 is 2A. What is the current through bulb 2?
VS = 5.5V (s for supply)
V1 = 2V
V2 = ?
VS = V1 + V2
5.5 = 2 + V2
V2 = 5.5 - 2 = 3.5V
I2 = I1 = 2A
- State the rule for current in parallel circuits.
The sum of the currents in parallel branches is equal to the supply current.
- State the rule for voltage in parallel circuits.
The voltage across components in parallel is the same as the supply voltage for every component.
- Explain the function of switches connected in series.
When more than one switch is connected in series they all have to be closed to complete the circuit and allow current to flow.
