Electricity Flashcards
How do things get an electrical charge?
By transferring electrons from on substance to another. Gentle friction is enough. The result is a positively charged and a negatively charged substance
What are conductors?
Electrons jump from one atom to another easily, readily flows through the substance. This is a conductor.
What are insulators?
Electrons cannot flow easily. Can be charged with static electricity, but won’t allow a flow of electrons.
Examples of conductors
Metals, Graphites, Salt water
Examples of insulators
Plastic, glass, wood, air, pure water
What’s an energy converter?
Something the electrons go through with resistance such as a lightbulb, heater or motor.
What are electrostatic forces?
Forces caused by 2 electrically charged objects acting across an electric field. Can be attractive or repulsive.
A push or a pull between two charged substances.
What’s electricity?
The flow of electrons. As these electrons hit objects, they are able to do things to them.
What are the 3 main concepts?
Current, Voltage, Resistance
What’s current?
How much charge ( how many electrons)are flowing past a point per second.
What’s voltage?
Energy each electron has. Can be provided by a battery.
What’s resistance?
How much the objects in the circuit (for example the material in the wire, or a light-bulb) resist the motion of these electrons.
Symbol and Unit for Current
Amperes (I)
Symbol and Unit for Voltage
Volts (V)
Symbol and Unit for Resistance
Ohms (R) Ω
What’s a series circuit?
- closed circuit
- not common in homes
- unreliable wiring method
- failure effects all devices
- higher resistance, so lower current and power
- each device cannot be controlled independantly
What’s a parrallel circuit?
- closed circuit
- common in homes
- reliable wiring method
- failure doesn’t effect all devices
- each device can be turned on or off independantly
What measures current?
Ammetre
What measures voltage?
Voltmetre
What’s Ohms Law
Current = Voltage
———–
Resistance
I=V
—
R
I=Amps
V=Volts
R=Ohms
What is power?
The amount of electrical energy converted per
second. Measured in “watts” (W).
What are the types of current?
Alternating, Direct
What happens in a direct current?
The electrical current produced by a battery
flows steadily from the -ve terminal to the
+ve terminal. The electrical field of a battery is constant and always points in the same direction.
What happens in an alternating current?
The electrical field moves back-and-forth rapidly. Electrons do not flow steadily, but jump back-and-forth.
Formula for electrical work?
Work done = force × distance
Formula for charge?
Charge = current × time
Q = I x t
What’s actual current?
Flows from negative terminal to positive (electrons).
What’s conventional current?
Flows from positive terminal to negative (positive charge).
