National 5 Electricity Flashcards
Label the following model of the atom, indicating the charge of each particle.
How many types of electric charge are there, and what are their names?
There are two types of electric charge - positive and negative
How do the types of electric charge interact?
Opposites attract - positive and negative
Like charges repel - positive and positive or negative and negative
What is an electric field?
An electric field is the space around a charged particle where another charged particle will experience a force.
Describe what would happen to a positive charge if it was placed in the field shown.
A positive charge would accelerate towards the negative plate.
Sketch the path of an electron at point A which moves towards the point charges shown in the diagram as shown and reaches point B
The electron is attracted by the postive charge but repelled by the negative charge, as shown.
Describe what would happen to a negative charge if it was placed in the field shown.
A negative charge would accelerate towards the positive plate.
In the diagram shown, what type of charge does the particle have?
Explain your answer.
The particle has a negative charge.
The particle is negative because it is attracted to the positive plate.
What effect does an electric field have on a conductor?
An electric field will cause the free electrons in a conductor to drift towards the positive end of the battery.
Explain in words what is meant by current.
An electric current if a flow of charge.
What is the numerical definition of current?
Current is how much electrical charge flows (past a point) in one second.
Q = It
(Define symbols and their units)
Q - charge (C)
I - current (A)
t - time (s)
Example
Calculate the current flowing during a bolt of lightning which lasts for 10 ms and transfers 50 C of charge.
Q = 50 C
I = ?
t = 10 ms = 10 x 10-3 s
Q = It
50 = I x 10 x 10-3
I x 10 x 10-3 = 50
I = 50/10 x 10-3
I = 5000 A
What does DC stand for and what does it mean?
DC stands for direct current, which means the electron current flows in one direction only (negative to positive).
What does AC stand for, and what does it mean?
AC stands for alternating current, which means that the current periodically reverses direction..
What is meant by the peak voltage of an AC supply?
The peak voltage of an AC supply is the maximum voltage it reaches in its cycle.
What is the quoted voltage of an AC supply?
The quoted voltage is an average value which enables fair comparison with a DC battery.
How do quoted and peak voltage compare?
Peak voltage is greater than quoted voltage.
What is the quoted voltage of the UK mains?
230 V
What is the frequency of the UK mains?
50 Hz
The voltage of a supply is a measure of the ………………. given to the charges in a circuit.
The voltage of a supply is a measure of the ENERGY given to the charges in a circuit.
Describe how to use an ammeter to measure the current in a component. Draw a diagram showing how an ammeter is connected.
An ammeter must be connected in series with a component.
Describe how to use a voltmeter to measure the voltage across a component. Draw a diagram to show how a voltmeter is connected.
A voltmeter must be connected in parallel with a component.
State the circuit rule for current in a series circuit.
The current in a series circuit is the same at all points OR
Is = I1 = I2 = …
State the circuit rule for voltage in a series circuit.
The voltages across the components in a series circuit adds up to the supply voltage OR
Vs = V1 + V2 + …
State the circuit rule for current in a parallel circuit.
The current entering in a parallel circuit divides into smaller currents through each component OR
Ip = I1 + I2 + …
State the circuit rule for voltage in a parallel circuit.
The voltage in a parallel circuit is the same across all components OR
Vp = V1 = V2 = …
What is the name of this component?
L.D.R. (light-dependent resistor)
What is the name of this component?
Cell
What is the name of this component?
Resistor
What is the name of this component?
Battery
What is the name of this component?
Lamp
What is the name of this component?
Motor
What is the name of this component?
Capacitor
What is the name of this component?
Current can only flow through this component in one direction - which?
Diode
Current can only flow ‘against the arrow head’ e.g. here, right to left.
What is the name of this component?
Variable resistor
What is the name of this component?
npn transistor
What is the name of this component?
Loudspeaker
What is the name of this component?
Fuse
What is the name of this component?
Switch
What is the name of this component?
Thermistor
What is the name of this component?
Photovoltaic Cell (Solar Cell)
What is the function of a cell or battery?
(including the energy change)
A cell or battery supplies the energy for a circuit, converting chemical energy to electrical energy.