Physics P1 Flashcards
(26 cards)
What is specific heat capacity?
The amount of energy required to heat up a kilogram of a substance by 1 degree
Why does the IV graph of a diode look like tat?
The current through a diode only flows through 1 direction, in the other direction, resistance is extremely high
As the temp of a thermistor increases does resistance inrease/decrease.
Resistance decrease
What is special about the potential difference, current and resistance in a series circuit?
Current is equal all around
Potential difference is shared between components
Resistance of all resistors is total resistance
What is special about the potential difference, current and resistance in a parallel circuit?
Current is shared between components
Potential difference is equal everywhere
Resistance decreases with more resistors
Is mains supply in the UK ac or dc current?
AC
What is an alternating current and what causes it?
It’s caused by an alternate potential difference (one that goes from positive to negative)
AC means the current periodically changes direction/reverses
What is the voltage and freq of the mains supply?
230V and 50Hz
Why are step up transformers used?
Large amounts of energy need to be transmitted by the mains supply.
This means that a high current should be used, however, this generates lot of heat due to high resistance - meaning energy is wasted
Instead, a high potential difference is created to reduce dissipated energy.
What voltage do step up transformers create?
400,00V
What voltage do step down transformers create?
230V
Why are step-down transformers necessary?
High voltage created from step up transformers is extremely dangerous and can cause electric shocks and blow up appliances
What is the purpose of the live wire and what color is it?
The live wire carries the alternating current and it is brown
What is the purpose of the neutral wire and what color is it?
It completes the circuit and is blue
What is the purpose of earth wire and what color is it?
It carries current to the earth if there is a fault with the circuit and it’s green with yellow stripes
What are the voltages of the 3 wires
Earth - 0V (unless there’s a fault)
Live - 230V
Neutral - 0v
specific latent heat?
the amount of energy required to change the state of 1kg of a substance without changing the temperature
specific latent heat of fusion?
change of state from solid to liquid
specific latent heat of vaporisation?
change of state from liquid to vapour
what is activity and what is it measured in?
activity is the overall rate of decays in a radioactive sample (measured in Bq, becquerels)
what is half life? 2 definitions
- time taken for number of radioactive nuclei in a sample to halve
- time taken for activity to halve
Qualities of alpha radiation?
- Highly ionising
- Not penetrating (stopped by paper and can only travel a few cm in air)
Qualities of beta radiation?
Moderately ionising
Somewhat penetrating (can go through paper but is stopped by a few mm of aluminium, can travel 1m in air)
