# Electricity Flashcards

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1
Q

What is the equation for energy transferred?

A
```E = V x Q
Energy transferred = Voltage x Charge
or
E = V x I x t
Energy transferred = Voltage x Current x Time```
2
Q

What is the equation for potential difference?

A
```V = W / Q
Voltage = Work Done / Charge```
3
Q

What is the unit for charge?

A

Coulombs

4
Q

What is the unit for work done?

A

Joules (J)

5
Q

What is Ohms Law?

A

V = I x R

6
Q

What is the equation for charge?

A
```Q = I x t
Charge = Current x Time```
7
Q

What is the rule for CURRENT in a SERIES circuit?

A

Current is the SAME everywhere in the circuit.

I1 = I2 = I3

8
Q

What is the rule for VOLTAGE (or P.D.) in a SERIES circuit?

A

The voltages of all the components ADD UP to the voltage of the battery.
V Battery = V1 + V2 + V3

9
Q

What is the rule for CURRENT in a PARALLEL circuit?

A

The current in each branch ADDS UP to form the total current going in and out of the battery.
I Total = I1 + I2 + I3

10
Q

What is the rule about VOLTAGE (or P.D.) in a PARALLEL circuit?

A

The voltage of each branch is the SAME as the battery voltage.
V Battery = V1 = V2 = V3

11
Q

What is the rule about RESISTANCE in a SERIES circuit?

A

Total resistance is equal to the resistance of all the components ADDED UP.
R T = R1 + R2 + R3

12
Q

What is the rule about RESISTANCE in a PARALLEL circuit?

A

1/RT = 1/R1 + 1/R2 + 1/R3

13
Q

How can you tell if a graph is directly proportional?

A

The line is straight and goes through the origin.

14
Q

What does a directly proportional V/I graph tell you about a component?

A

It is an Ohmic resistor.

15
Q

What is current?

A

The flow of charge (electrons).

16
Q

What is a battery?

A

Two or more cells connected together.

17
Q

What does Ohm’s law state?

A

Current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.

18
Q

What does the gradient of the line in a V/I graph tell you about the component?

A

The steeper the line, the greater the resistance.

19
Q

What is an Ohmic resistor and a Non-Ohmic resistor?

A

Ohmic
• Straight line through origin (V/I graph)
• Resistance does not change with increased current
Non-Ohmic
• Curved line (V/I graph)
• Resistance changes with increased current

20
Q

Why does resistance increase with current in Non-Ohmic resistors?

A

Greater current heats up the wire. This causes the ions in the metal to vibrate more, blocking flow more and therefore increasing resistance. The result is a curved graph.

21
Q

What are some examples of Non-Ohmic and Ohmic resistors?

A
```Ohmic
• Fixed Resistor
Non-Ohmic
• Filament Bulb
• Diode```
22
Q

What does the V/I graph look line for a fixed resistor?

A

Straight line through the origin.

23
Q

What does the V/I graph look line for a filament bulb?

A

It curves away from the current axis as current increases.

24
Q

What does the V/I graph look line for a diode?

A

Along the voltage axis until a certain current, then sudden spike up.

25
Q

What does a diode do?

A

Allows current to flow in one direction. Very high resistance one way, very low the other way.

26
Q

What does an LDR (Light Dependent Resistor) do?

A

Resistance increases as light intensity decreases.

27
Q

What does a thermistor do?

A

Resistance increases as heat decreases.

28
Q

What experiment can be used to work out the resistance of a wire/component?

A
• Circuit with battery, variable resistor, ammeter, component and a voltmeter around it.
• Variable resistor is used to change current.
• At various currents, the potential difference is recorded.
• A V/I graph can be plotted.
• R = V/I can be used to calculate the resistance.
29
Q

Other Stuff To Revise…

A
• Different component symbols and functions

* Drawing V/I graphs