Studied by 4 people
Define a scalar quantity
It is a magnitude. It can be described fully with a single numerical value
Give 2 examples of a scalar quantity
mass and speed
Define a vector quantity
it has both a magnitude and a direction
Give 2 examples of a vector quantity
Velocity and displacement
Which property of a distance-time graph can be used to calculate speed?
Gradient (Slope)
what is this d-t graph showing?
constant speed
what is this d-t graph showing?
at rest
what is this d-t graph showing?
accelerating
State an equation linking distance moved, time taken and average speed with their respective units.
Average speed(m/s) = Distance(m) / Time(s) or v=d/t
What is meant by acceleration? Give its unit.
the change in velocity per unit of time. m/s2
State an equation linking acceleration, change in velocity and time taken
Acceleration =(Change in velocity)/ time or a = (v-u) / t
v is final velocity and u is initial velocity
Which property of a velocity-time graph can be used to calculate acceleration?
Gradient (slope)
Which property of a velocity-time graph can be used to calculate distance travelled?
Area under the graph
What is this v-t graph showing?
constant speed
What is this v-t graph showing?
accelerating
What is this v-t graph showing?
decelerating
State an equation linking final speed, initial speed, acceleration and distance travelled
v2 = u2 + 2as
Identify force A acting on the objects
weight
Identify force B acting on the objects
air resistance (drag)
Name two types of forces that always opposes motion
friction and air resistance (drag)
Which type of force holds planets around the Sun?
Gravitational Force
Which type of force holds electrons around nucleus?
Electrostatic Force
State the ways that a force can affect the body that it is being applied on.
change the shape (extension/compression). change the speed. change the direction the object is moving
Calculate the resultant force for the object and state the direction
5N to right
Calculate the resultant force for the object and state the direction
0N (balanced)
Calculate the resultant force for the object and state the direction
13N downwards
What magnitude would the resultant force have and in what direction would it be pointing?
45N to left
State an equation linking unbalanced force, mass and acceleration
Force(N) = Mass(kg) x Acceleration (m/s2) or F = m x a
State an equation linking mass, weight and gravitational acceleration
Weight(N) = Mass(kg) x g(m/s2) or W = mg
What is the relationship between stopping distance, braking distance and thinking distance of a car while stopping?
Stopping Dist. = Thinking Dist. + Braking Dist.
State 4 factors that affect the stopping distance of a car
Reaction time, Mass of the car, Initial speed, Weather conditions
State two factors that affect the air resistance acting on a falling object
surface area and speed
Describe how a falling object reaches to terminal velocity
At first object falls under the effect of its weight accelerating with g. As it accelerates, air resistance opposing the motion increases therefore resultant force acting on the object decreases and since F=ma, acceleration decreases. When air resistance becomes equal to weight, forces are balanced so resultant force=0 therefore a=0 and object reaches to terminal velocity.
State what is meant by obeying Hooke’s Law
Extension is directly proportional with the force applied
Explain what is the difference between elastic and plastic behaviour
elastic behaviour - object recovers its original shape when the forces causing the extension is removed
plastic behaviour - a permanent deformation to the shape of the object when forces are removed
What three main components make up an atom?
electrons, protons and neutrons
Describe the structure of an atom in terms of the position of its components?
Neutrons and protons are in the nucleus while Electrons surround the nucleus in shells
An atom contains two types of charged particles, name both of them and state their charges?
Proton (+1) and Electron (-1)
This symbol represents a cell. Which side is the positive terminal?
The left longer side
Which of these two symbols represents a resistor?
A
What does this symbol represent?
a diode
Which component does this symbol represent?
a thermistor
How is a thermistor affected by changes in temperature?
As temperature increases, its resistance decreases
What appliance does this symbol represent?
A Variable resistor
What does this symbol represent?
A LDR (Light Dependent Resistor)
Voltage is also known as…
Potential difference
What is a series circuit
when all components are connected in the same loop
what is a parallel circuit
when the components are on different loops
What are the differences between series and parallel circuits in regards to current and voltage?
series - The same current flows through all the components. The potential difference across the components is not the same. The total potential difference is equal to the sum of potential differences across each component
parallel -The current flowing in a junction is equal to the current leaving it. The sum of the currents in each section is equal to the total current. The potential difference across each branch is the same.
Where must a voltmeter be placed in a circuit?
In parallel with the component that is being measured
Give an equation relating potential difference with energy transferred and charge
Voltage(V) = energy transferred(J) / charge(C) or V=E/Q
A volt can also be described as a...
Joule per coulomb
What is an electric current?
The rate of flow of charge
What is an ammeter and where must it be connected in a circuit?
it measures current. It is placed in series with the component it is required to measured.
What equation including time and current can be used to measure charge?
Charge(C) = Time(s) x Current(A) or Q = I x t
In a closed circuit, if there is a potential difference in the circuit there will also be a ...
current
State an equation linking current, voltage and resistance with their units
Voltage(V) = Current(A) x Resistance(Ω) or V = I x R
How does changing the resistance in a circuit change the current?
Current is inversely proportional to resistance. Therefore at a constant voltage, increasing the resistance will decrease the current. In an electrical circuit the flow of electrons causes a current. A high resistance makes it harder for electrons to pass through and therefore reduces the current.
How can you use a variable resistor to increase the current in a series circuit?
You set the variable resistor to have a lower resistance, this should increase the current.
Why does the net resistance of two resistors in parallel decrease?
In parallel
- IT = I1+ I2+ I3
- V1 = V2 = V3
Therefore 1/RT = 1/R1 + 1/R2 + 1/R3
Explain the relationship between voltage, current and resistance in a filament lamp.
As temperature increases in the lamp, the resistance also increases. This is because a higher temperature makes the ions in the filament vibrate more, making it harder for electrons to pass through. This therefore decreases the current. A filament lamp is not ohmic, meaning that current is not directly proportional to the potential difference. If voltage is double, current will not be doubled since there will be an increase in resistance
How do diodes work?
It only allows current to flow in one direction. If current is flowing the right way, the resistance is very large at small voltages (up until about 0.6V), but then at higher voltages the resistance becomes very small.
Describe the relationship between thermistors and resistance
The resistance of a thermistor changes with temperature, therefore when the temperature increases the resistance decreases.
How does a LDR work?
The resistance of a LDR varies with light. As the light intensity increases the resistance decreases and vice versa.
What electrical component does this graph represent?
diode
When an electrical current flows through a resistor why does it heat up?
There are collisions between the electrons and the ions in the resistor’s lattice. This causes a transfer of kinetic energy into thermal energy, which is released into the surroundings.
How do low resistance wires reduce unwanted energy transfers?
A smaller resistance will mean there are fewer collisions, therefore less energy will be wasted through heating.
What is an advantage of the heating effect?
Can be used for appliances such as toasters or electrical fires, where the hot wire helps heat the bread or room
What are some disadvantages of the heating effect?
The loss of energy as heat energy can make an appliance inefficient and If an appliance overheats it can catch fire or overheat, which could ruin the device or injure the user
State the equation linking electrical energy transferred, voltage, current and time
E = I(current) x V(voltage) x T(time)
The energy transferred per second is also known as...
Power (in Watts)
State an equation linking electrical power, current and voltage
Power = Current x Voltage or P = I x V
Give an equation for power in terms of current and resistance.
P (power in W) =I2 (current2 / A2) x R (resistance in Ω) or P=I2 x R (Sub V=IR into P=IV)
What is meant by direct current?
Current flows only in one direction
What is meant by an alternating current?
Direction of current changes continuously as time passes
what does this voltage-time graph supply?
Alternating Current
what does this voltage-time graph supply?
Direct Current
What type of current do batteries and cells supply?
direct current
What is the difference between the function of the live and the neutral mains input wires?
Live wire - supplies voltage and forms current within the circuit. considered dangerous
neutral wire - carries current away from the appliance and completes the circuit allowing current to flow
How does an earth wire ensure safety?
connected to the metal casing of the device and provides a low resistance path to the ground. if a fault occurs it allows the large currents in the live wire to flow through to the ground
What colour is the live wire?
Brown/Red
What colour is the neutral wire?
Blue
What colour is the earth wire?
Green and yellow
How does a fuse wire stop the device from getting damaged?
When a fault occurs and there is an excess current flow, fuse melts(blows) and disconnects the live wire. Current flow must be greater than fuse rating for fuse to blow.
Why is it important to connect a fuse or switch to the live wire?
When the switch is turned off, or when the fuse breaks, it will break the circuit and stop current running through the wire since live wire carries the voltage.
Some appliances are said to be double insulated. Explain what is meant by double insulation.
When casing of an appliance is made out of plastic, it is said to be double insulated since plastic is an insulator and does not let electricity pass through
Which connection is not required when the appliance is double insulated? Give a reason for your answer.
Earth wire is not required. Because earth wire is connected to the casing of the material. If casing is made out of plastic(insulator), earth wire will not be able to let the current flow to the ground.
Circuit breakers can be used instead of fuses. Give 3 advantages of circuit breakers over fuses
More sensitive, Easier to reset, Does not need to be replaced
Complete this sentence. Waves transfer ______ and ______ without transferring _______.
energy
Complete this sentence . Waves transfer ______ and ______ without transferring _______.
information
Complete this sentence . Waves transfer ______ and ______ without transferring _______
matter
Define frequency and give its units
The number of waves passing through a point per second. Hz (hertz)
Define wavelength
The distance between two adjacent peaks on a wave
Define amplitude
The maximum displacement of the wave from its equilibrium position. The distance between the centre of the wave and a peak
What is meant by the period of the wave?
The length of time it takes for one full wave to pass through a point
How can you calculate the wave speed?
Wave speed (m/s) is equal to the product of the wavelength and the frequency of the wave
State the equation to calculate wave speed?
Wave velocity= f ×λ
State an equation linking frequency and period of a wave
Frequency (Hz) = 1/period(s) or f = 1/T
What is a longitudinal wave?
Vibrations are parallel to the direction of energy transfer
Examples of a longitudinal wave
sound waves and earthquakes (seismic waves)
Note 
Flashcard (63)