science unit 6 Flashcards
what is electrical current
The rate of flow of electrons in a circuit
SI unit of electrical current
Ampere (A)
what is e.m.f.
Work done by the source in driving a unit charge around a complete circuit
SI unit of e.m.f.
volt (v)
what is potential difference
a measure of the amount of energy that is changed into other forms of energy when a unit of charge passes between these 2 points
The work done to drive a unit charge across an electrical component
what is resistance
ratio of the potential difference across it to the current flowing through it
properties of resistance
The higher the resistance in a circuit, the higher the potential difference needed to move electric charge through the component
R=V/I (V=voltage I=current)
SI unit: Ohm
The greater the ratio of V to I, the greater the resistance
The greater the resistance in a circuit, the lower the current
series circuit properties
Each component is joined one after the other to form a single path. The current that flows through each of the components is the same.
If one bulb is removed or broken, no current flows, and the other bulbs do not light up because the circuit is now open.
Current is same throughout the circuit
V1 +V2 …..Vn
Component with the largest resistance has the highest voltage
R=R1 +R2……Rn
parallel circuit properties
The current from the battery divides and flows through each branch.
If one bulb is removed or broken, the other bulbs remain lit because the circuit remains
I=I1+I2+…..In
Branch with the least resistance will have the largest current flowing through it
resistance is the same throughout
effect of current
heating effect
magnetic effect
chemical effect
electric power
SI unit of power : watt (W). 1kw= 1000w Energy consumed (in kwh)= Power (in kW) x Time (in hours)
