physics 4 Flashcards
(16 cards)
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?
- an invisible force field created by the attraction and repulsion of electrical charges
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?
- charge -> coulombs (C)
- current -> amperes (A)
- time -> seconds(s)
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 (Ω)
- 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?
a conductor that maintains a constant resistance over a wide range of voltages
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
What are the main features of a parallel circuit?
- p.d. across each branch is the same
- total current
through circuit is the sum of the currents in each
branch
