P5 - Electricity in The Home Flashcards
What is meant by the term voltage?
The push from a battery.
What is voltage an alternative word for?
Potential difference (pd)
What are the units and symbol of voltage/potential difference?
Voltage, V
Volts
How is voltage measured?
Using a voltmeter.
What is meant by the term current?
The flow of electrons and how fast they flow.
What is an alternative defitinion of current?
The charger per second.
*think ‘c’ for current and ‘c’ for charge.
What are the units and symbol of current?
Current, I (I for intensity)
Amperes/amps (A)
How is current measured?
Using an ammeter.
What is meant by the term power?
The rate of which energy is transferred per second.
P = E/t
What are the units and symbol of power?
Power, P
Watts (w)
What is the equation used to calculate the power supplied to an electrical appliance?
Power = Current x Voltage
P = I x V
(W) = (A) x (V)
What does charge mean?
The property of a body which experiences force in an electrical field.
What sub-atomic particles are ‘charge carriers’?
Electrons
What is the symbol and unit of charge?
Charge, Q
Coulombs, C
What is the charge of an electron?
1.6 x 10^-19 coulombs
How is charge calculated?
Charge = Current x time
Q = I x t
(C) = (A) x (s)
What is meant by the term resistance?
Refers to how much the flow of electrons is reduced.
*how much of the push from the battery is effecting the current.
What are the units and symbol of resistance?
Resistance, R
Ohm’s (Ω)
How do you calculate resistance? Ohm’s Law:
Ohm’s Law:
Resistance = Voltage / Current
R = V / I
(Ω) = (V) / (A)
How do you caulculate the energy supplied to a circuit? *Used in RP1.
Energy = Current x Voltage x time
E = IVt
(J) = (A) x (V) x (s)
Working out:
E = Pt
we know P = IV
so E = IVt
What is the equation for power supplied to the resistor?
Power to resistor = (current)^2 x resistance
P = I^2 x R
(W) = (A)^2 x (Ω)
Why is the power to a resistor equal to I^2 x R?
Combine Ohm’s Law (R=V/I) with P = IV
Substituting V = IR into P=IV gives P = I(IR) = I^2R
P = I^2 x R
How do you calculate the energy supplied to a resisitor?
Energy to a resistor = Charge x Voltage
E = *Q x V
(J) = (C) x (V)
*Q = It
So this equation is essentially E = ItV, the same as E = IVt for normal electrical energy.
What is the equation for calculating the cost of electricity?
Cost of Electricity = Power x Time x Unit Cost
Pence, p) = (kW) x (hrs) x (pence/kWh
What is the unit cost also referred to as?
Tariff - the cost per kilowatt hour (p/kWh)
What would the cost of electricity be if 10W of energy is supplied in 24 hours, with a unit cost of 12 pence/kWh?
Cost = P x t x kWh
10 W = 0.01kW
= 0.01kW x 24 x 12 = 2.88p
