National 5 EE Flashcards
What is electric current?
The movement of a group of electrons around a circuit.
What is the equation involving charge, current and time?
Current= charge/ time I= Q/t
What is the difference between alternating and direct current?
A.C is produced from the mains supply. The electrons flow around in one direction then the direction changes and the electrons flow in the opposite direction.
D.C is prodcued from a battery. The electrons always flow in one direction around the circuit
What is the effect of an electric field on a negative charge?
It would be accelerated towards the positive plate due to both replusion of the negative plate and the attraction to the positive plate.
What is the potential difference between two parallel charged plates?
A measure of the energy given to the charges when they move between the plates.
What is the equation involving resistance in series?
RT= R1+ R2+ R3
What is the equation involving resistance in parallel?
1/RT= 1/R1+ 1/R2+ 1/R3
What is the equation involving potential difference, current and resistance?
Voltage= current x resistance V= I x R
What is the equation involving potential difference and resistance in potential divider circuits?
V1/ V2= R1/ R2
What is a transistor?
A process device that acts as an automatic switch (voltage operated)
What is the difference between heat energy and temperature?
Heat: a form of energy and is measured in joules.
Temperature: a measure of how hot or cold something is and is measured in degrees celsius.
What is the temperature of a substance?
A measure of the average kinetic energy of the particles in that substance.
What is meant by the specific heat capacity of a substance?
The amount of heat energy required to change the temperature of 1kg of a substance by 1°C.
What is the equation involving specific heat capacity?
Heat energy= specific heat capacity x mass x change in temperature
Eh= cm (Delta) T
What is the Principle of Conservation of Energy?
Energy cannot be created or destroyed. Energy is always conserved (it can be changed from one form into another)
What is the unit of energy?
Joules (J)
What are examples of energy transformations?
Light bulb: electrical energy—-> light energy (and heat energy)
Hoover: electrical energy—-> kinetic energy (and sound energy)
What is the symbol for work done?
Ew
What is the equation involving work done, force and displacement?
Work done= force x displacement
Ew= F x s
What is gravitational potential energy?
The work done against gravity.
What is the symbol for potential energy?
Ep
What is the equation involving potential energy, mass, gravitational field strength and height?
Potential energy= mass x gravitational field strength x height
Ep= m x g x h
What kind of energy does a moving object have?
Kinetic energy
What is the symbol for kinetic energy?
Ek
What is the equation involving kinetic energy, mass and velocity?
Ek= 1/2 x m x v squared
What is pressure?
The force exerted on a surface per one metre squared
What is the unit of pressure?
Nm-2
Pascals, Pa
What is the equation involving pressure, force and area?
Pressure= force/ area P= F/A
What is the general gas equation?
p1 x V1/ T1 = p2 x V2/ T2
What is absolute zero?
-273°C is 0 on the Kelvin temperature scale.
At absolute zero, all particle motion stops and this is therefore the lowest possible temperature.
How to you convert degrees celsius into kelvin?
Add 273
How to you convert kelvin into degrees celsius?
Subtract 273
