Physics Yr 10 Flashcards
What are the 6 renewable energy sources?
•tidal
•solar
•wave
•hydroelectricity
•wind
•biomass
What are the 4 non-renewable energy sources?
•gas
•coal
•oil
•nuclear
Renewable meaning
Can be easily replaced
Non-renewable meaning
Cannot be easily replaced
Coal advantages and disadvantages
Advantages:
•efficient
•reliable
Disadvantages:
•produces CO2 which contributes to global warming
•produces SO2 which contributes to acid rain
Wind advantages and disadvantages
Advantages:
•doesn’t need fuel
•doesn’t contribute to the greenhouse effect
Disadvantages:
•unreliable
Nuclear advantages and disadvantages
Advantages:
•reliable
• doesn’t contribute to the greenhouse effect
Disadvantages:
•nuclear waste is difficult and expensive to remove
•target for terrorist attacks
Geothermal advantages and disadvantages
Advantages:
•doesn’t contribute to the greenhouse effect
•doesn’t need fuel
Disadvantages:
•not many places to build geothermal power stations
•hazardous gases and minerals may come up from underground
Tidal advantages and disadvantages
Advantages:
•doesn’t contribute to the greenhouse effect
•doesn’t need fuel
Disadvantages:
•changes the environment for miles upstream and downstream
•only provides power when the tide is moving in or out (~10hrs a day)
Hydroelectricity advantages and disadvantages
Advantages:
•can be used at times of high demand
•more reliable than other renewable energy sources eg wind or solar
Disadvantages:
•expensive
•building a dam will cause areas to flood
• finding a suitable site can be difficult
How do wind power stations work?
Wind turns a turbine which turns on a generator and produces electricity
How do coal power stations work?
Burning coal produces heat and turns water to steam, which turns a turbine that turns on a generator to produce electricity
How do hydroelectric power stations work?
Water is pumped up through a pipe from a bottom lake to a top lake to be stored at times of low demand. The water is allowed to flow down the pipe at times of high demand to produce instant electricity.
How to find the efficiency of an appliance?
(Useful energy / total energy) x 100
Definition of current
The flow of electrons around a circuit or through a wire
Definition of voltage
The energy that pushes the electrons around the circuit
How does current work in a series circuit?
It’s the same everywhere
How does current work in a parallel circuit?
It splits at junctions
How to find the total current in a parallel circuit?
Sum of the all currents in the junctions
At = A1 = A2 + A3
How does voltage work in a series circuit?
It splits across components
How does voltage work in a parallel circuit?
It’s the same across each loop
How to find the voltage in a series circuit?
Vt = V1 + V2
Definition of resistance
How hard it is for current to flow
What are the 3 practicals in the electricity topic?
Current and voltage of a:
•wire or resistor
•bulb
•diode
What does the line graph look like on the wire or resistor practical?
A straight line
What does the graph look like on the bulb practical?
A curve that goes from steep to flat
What does the graph look like on the diode practical?
A curve that goes from a steady incline to steep, which only forms once a certain voltage is reached
How does resistance work on a wire or resistor?
The resistance doesn’t change
How does resistance work on a bulb?
The resistance increases as the voltage and current increase
What is the method for all the practicals on the electricity topic?
- Set up a series circuit with a cell, ammeter, variable resistor and a voltmeter going across a wire/bulb/diode
- Move the variable resistor so that the voltmeter reads 0V
- Use the variable resistor to get a range of voltages eg: 2V, 4V, 6V, 8V, 10V
- For each voltage record the current
- Plot the data on a line graph or table
How does resistance work in a series circuit?
The more components in the circuit, the higher the resistance
How to find the total resistance in a series circuit?
Rt = R1 + R2
How to find the total resistance in a parallel circuit?
1/Rt = 1/R1 + 1/R2
Flip the answer
What are step-up transformers used for?
Increasing the voltage and decreasing the current of the electricity in power lines to reduce the amount of energy wasted as heat energy
What are step-down transformers used for?
Decreasing the voltage to a safe level (230V) and increasing the current
What is direct current?
Always flows one way around the circuit
What is alternating current?
The size and direction of the current is always changing
What supplies direct current?
Batteries
What supplies alternating current?
The National Grid
What are the wires in a plug?
Live, neutral and earth
What does the live wire do?
Carries the current to the appliance
What does the neutral wire do?
Completes the circuit and carries the electricity back to the consumer unit
What does the earth wire do?
Provides a safe route for the current to flow to the ground if the live wire touches metal casing
How does an MCB work?
If too much current flows an electromagnet breaks the circuit
How does an RCCB work?
If there is a difference between the current in the live and neutral wire an iron pivot breaks the circuit
How does a fuse work?
If too much current flows through the wire in the fuse, it melts and the circuit is broken
Does an MCB protect the user or the circuit?
The circuit
Does an RCCB protect the user or the circuit?
The user
Advantages of circuit-breakers over fuses
•respond quicker than fuses
•more reliable
•more sensitive
•can be reset (unlike fuses)
What equation is used to find how much units of energy an appliance uses?
Energy (KWh) = Power (KW) x time (hours)
How to find how many units have been used using metre readings?
Present reading - previous reading
What formula is used to find out density?
Density = mass/volume
