Electricity Flashcards
What is current
The rate at which an electric charge passes a point in a circuit
What do you need for current to flow
- A complete circuit 2. A cell, battery, or power supply
Name 3 tools to measure current
- Analouge meter 2.Digital meter 3. Galavameter
What is an ammeter
An ameter is used to measure current
What unit of measurement an ammeter use
Amperes
What type of circuit is an ammeter connected to
Series
What is the formula to measure current
Current(a) = Charge(coloumbs)/Time(s), Q(Charge)=I(Current) T(seconds), Q=IT
A current of 150mA flows for 1 minute. What is the charge?
9C
What is the definition of voltage?
The difference in elecrtical potential between 2 points, or How much work is done to move one coloumb of charge.
What is used to measure voltage
Voltemeter
What is the unit for voltage?
Volt
What circuit is the voltmeter connected to?
Parallel circuit
What is EMF
Electromagnetic Force
What is the definition of EMF
The energy provided by a source to move electrons through a circuit
What is the EMF of two batteries with the voltage of 1.5
3.0 Volts
What happens if a battery is connected in reverse?
It cancels out
What is the formula to calculate Voltage?
Voltage= Work done(W)/ Coloumbs(Q), V=W/Q, V=Jules/Charge OR V=IR
A battery that gives 60J of energy to a charge of 5C, work out the voltage
V=W/Q
=60/5
=12V
A circuit has a voltage of 12V within 10 seconds and a current of 2 amperes. Calculate the work done
V=W/Q
Q=IT
Q=2 X 10
Q=20
V=W/Q
12=W/20
w=240j
What is the definition of resistance?
A measure of how difficult it is for an electric current to flow through a devices
What is the resitor symbol
-[ ]- (Not accurate)
What happens to the current if there is more resistance in a circuit
The less the current
What is the formula for resistance?
R=V/I
V- voltage
I- Current
R-Resistance
Calculate the resistance of a circuit with the current of 0.02A and a voltage of 10.0V
R=V/I
=10/0.02
=500
What is potential difference?
Potential difference is voltage (define voltage)
What happens to a current when a voltage increases
WHne voltage increases, current increase
WHat is an Ohmic Resistor
A resistor where regardless the voltage increase, the voltage will remain the same. Coonstant resistance
What is a Non-Ohmic Resistor
A resistor which changes with the current or voltage of a circuit
Name and explain 2 factors of resistance
1) Length-The longer the wire th e greater the resistance
2) Diameter -The thiker the wire the less the resistance. Halving the wire, doubles the resistance
What are Watts
The rate at which energy is used or transferred. Watts are power
Jules per second
What is the formula to measure power
P=VI
P-Power
V-voltage
I-Current
What is the formula to calculate energy
E=VIT
E-Energy
V-Voltage
I-Curent
T-Time
What is the formula to calculate energy transferred
E(KWH)=P(KW) X TIME
What happends to the current when resistence decreases
The current will increase
What is a LDR
An LDR (Light Dependent Resistor) is a resistor whose resistance changes based on the light it receives.
The more the light then the less the resistance
What is a thermistor
A thermistor is a type of resistor whose resistance changes with temperature. The higher the temperature = the lower the resistance
What are relays
a switch that is controlled by elctorcromagnets and is used with 2 complete circuits
What is a variable resitor
A resistor where resistance can be changed
When is a relay used
Relay is needed qhwn the circuit has a large voltage
How does an LDR work
Light has protons, and these protons energize the electrons,s making the current flow faster
What is a diode
A diode allows electric current ot flow in one direction
What is a LED
An LED is a diode that emits light when a current flows through it
How do you calculate resistance in a series
Theresistance is sumf of the resistance
How does voltage work in a series circuit
In a sereis circuit the voltage is shared across the circuit
How does voltage work in a parralel circuit
Voltage is the same throughout each component
How do you calculate resistance in a parallel circuit
1/R=1/R1 + 1/R2
Hod do you calculate current in a parallel and series circuit
I=I1+I2
WHat is a analogue circuit
It is a circuit that allows voltages to be in a certain range
What is a digital circuit
Voltages have one of two values, high (on) or low(0)
What is a logic gate
Logic gates are switching circuits
What is the truth table
The truth table is a table that shows the outputs for all possible inputs
When are logic gates used
As processes in electric control systems
Name and explain one use of a logic gate
Security systems used the And gate. If multiple sensors are on then alarm goes on
What do digital meters do
They display their readings as digits
What does an analogue meter do
Displays their reading on a continuas scale
What is a potential divider
A part of a circuit consisting of 2 resistors connected in series
What is the use of a potential divider
It helps control voltage in a circuit
What is the formula for potential dividers
V1/V2=R1/R2
