12.2- POTENTIAL DIFFERENCE AND POWER Flashcards
How do electrons move around a circuit with a bulb? (3)
each electron takes fixed amount of energy from battery as it passes through it
electrons then deliver energy to bulb as it passes through it
after delivering energy to bulb, each electron re-enters battery via positive terminal to be resupplied with more energy to deliver to bulb
What does a battery have? (hint: potential to?)
potential to transfer energy from its chemical store if battery not part of complete circuit
What happens when a battery is in a circuit?
each electron passing through circuit component does work to pass through component and so transfers some or all of its energy
Definition of potential difference
work done per unit charge
What is the unit of pd?
volt
Equation for voltage using work done?
V = W/Q
What is the emf of a source of electricity defined as?
electrical energy produced per unit charge passing through source
What is the unit of emf?
volt
When does an electric current have a heating effect? (2)
when it passes through a component with resistance
and magnetic effect
What is work done transferred into in a device that has resistance such as an electrical heater?
work done on device transferred as thermal energy
Why is the work done on device that has resistance, transferred as thermal energy?
as charge carriers repeatedly collide with atoms in device + transfer energy to them, so atoms vibrate more + resistor becomes hotter
What is the work done equal to in an electric motor turning at a constant speed and so what is the KE like?
work done on motor equal to energy transferred to load + surroundings by motors, so KE of motor remains constant
What are the charge carriers in an electric motor and what do they do?
electrons that need to be forced through wires of spinning motor coil against opposing force on electrons due to motor’s magnetic field
What is work done transferred to in a loudspeaker?
work done on loudspeaker transferred as sound energy
What do electrons need to do in loudspeakers?
electrons need to be forced through wires of vibrating loudspeaker coil against force on them due to loudspeaker magnet
