Any predictions on the experiments coming up? or any topic coming up? Hardwater, Ohm's Law, work/pressure, and dna are common topics to come up. Also Balancing equations come up almost every year. Can anyone explain to me how they work as I just don't understand them
this sheet is really helpfully you just need to learn them really
Its hard to predict experiments but these ones seem to come up most often....
* To show a plant produces starch during photosynthesis (it came up in 2015 - unlikely)
* Titration (Its likely to come up)
* To show the presence of CO2 in air (it came up in 2015 - unlikely)
* Chromatography (highly likely)
* Distillation (likely)
* Preparation of O2 (likely)
Other possible experiments...
* Seed Germination
* Conditions necessary for rusting
* To show CO2 is more dense than air
I hope this helps :)
I've got some Physics notes here.
A diode is a component that will allow a current to flow in one direction only.
When the positive terminal of a battery is connected to the positive end of the diode, it os called forward biased and it allows a current to flow.
If its in reverse bias, it won’t flow.
The code can be used as a rectifier to change a.c.to d.c.
LIGHT EMITTING DIODE
An LED gives out light when a current flows through it. It will only flow if it is forward bias.
They can only take small currents so a suitable resistor must be lined up in series to prevent from blowing the LED
LIGHT DEPENDANT RESISTOR
An LDR is a resistor whose resistance depends on light.
When light falls on it, its resistance decreases
ELECTRICITY IN THE HOME
Plugs have a live wire (positive) which is brown and connected on the bottom right of a plug
Plugs have a Neutral (Negative) wire which is blue and is connected to the bottom left of a plug
Plugs have an Earth wire which is green/yellow and is connected to the top of a plug
This is a safety wire which is connected to the metal casing on an appliance and runs to a plate buried in the ground.
A Fuse contains a thin piece of wire which heats up and melts when a current above a certain level passes through it
Although modern houses use circuit breakers which are switches with a bimetallic strip, they switch off if they heat up due to an electrical fault. They don’t have to be replaced.
The watt(w) is the unit of electrical power. The ESB uses the Kilowatt hour (kWh). It is the electrical energy used by a 1kw appliance running for 1 hour.
1. The number of units of electricity used by a 3kW heater in 4 hours
3kilowatts x 4 hours = 12 units
To calculate the cost of running an appliance, multiply the units by the cost per unit.
1. 12units x 15c = €1.80
Electrical power can be calculated using this formula
Power = Voltage x Current
The ESB provides current at a voltage of 220V
To find how much current an appliance uses
Current = Power divided by voltage
This can indicate what type of fuse to use, it should be slightly higher than the current.
DIRECT CURRENT AND ALTERNATING CURRENT
A direct current pushes the current in one direction only
An alternating current moves back and forward many times per second
Since a direct current is needed in some appliances and the ESB only provide alternating current since its cheaper, a rectifier is used to convert it to Direct current.