More on Power Flashcards
Electricity (13 cards)
What is the definition of potential difference?
Energy transferred per charge passed
Potential difference is the work done to move a charge between two points in an electric field.
What happens when an electrical charge goes through a change in potential difference?
Energy is transferred
Where is energy supplied to the charge in a circuit?
At the power source to ‘raise’ it through a potential
What does a charge do when it ‘falls’ through a potential drop in components elsewhere in the circuit?
Gives up energy
What is the formula for energy transferred?
E = QV
In the formula E = QV, what does each symbol represent?
- E = Energy transferred
- Q = Charge flow (C)
- V = Potential difference (V)
How does the potential difference of a battery affect the energy supplied to the circuit?
A battery with a bigger pd will supply more energy for every coulomb of charge
Calculate the energy transferred if 140 C of charge passes through a 3 V battery.
420 J
Calculation: E = QV = 140 * 3
What is the formula for calculating power in an appliance?
Power (W) = Potential difference (V) x Current (A)
What is the formula for current when power and potential difference are known?
I = P / V
If a 1.0 kW hair dryer is connected to a 230 V supply, what is the current through the hair dryer?
43 A (to 2 significant figures)
Calculation: I = 1000 W / 230 V
What is the relationship between power, resistance, and current?
P = I²R
True or False: The power of an appliance can be found without knowing the potential difference.
True
