P4 Electric Circuits Flashcards
How does a material become charged?
becomes negatively charged by gaining electrons and becomes positively charged by losing electrons
What will two objects carrying the same type of charge do if they are brought close to each other?
repel each other
What is an electric field?
region of space around a charged object in which another charged object will experience an electrostatic force
What happens to the strength of an electric field as you get further from the charged object?
it decreases
What is electric current?
rate of flow of charge
What units are charge, current, and time measured in?
coulombs (C), amperes (A), seconds (s) respectively
What is the same at all points when charge flows in a closed loop?
current
What must there be in a closed circuit so that electrical charge can flow?
source of potential difference (p.d.)
Which two factors does current depend on and what are their units?
resistance in ohms (0), p.d. in volts (V)
What happens to the current if the resistance is increased but the p.d. stays the same?
current decreases
What is an ohmic conductor?
conductor where current is directly proportional to the voltage so resistance is constant (at constant temperature)
What happens to the resistance of a filament lamp as its temperature increases?
resistance increases
What happens to the resistance of a thermistor as its temperature increases?
resistance decreases
What happens to the resistance of a light-dependent resistor when light intensity increases?
resistance decreases
What are the main features of a series circuit?
same current through each component, total p.d. of power supply is shared between components, total resistance of all components is the sum of the resistance of each component
