Current, Potential Difference & Resistance

Charge units

coulombs

Potential difference

________** is also known as voltage and is the amount of energy transferred per unit of charge passing through the terminals.

fuse

A(n) ________ is a safety device designed to cut off the flow of electricity to an appliance if the current becomes too large.

Wires

________ are made of metal because metal is a good conductor.

Current

Alternating ________ (ac) is a(n) ________ that is continuously changing its direction, going back and forth around a circuit.

Frequency of ac

________ is the number of times it changes back and forth each second, and it can be measured on an oscilloscope.

energy transferred

Work is done when charge flows through a circuit (work done= ________)

negative terminals

There are fixed positive and ________ in the electric cells or batteries.

rate of energy transfer

Power is the ________ or the amount of energy transferred per second.

Energy transfer

________ is calculated using the equation P= E /t. Since P= IV, you can also say that E= IVt.

Resistance

________ can be increased by adding ________, however, all of the components of a circuit do have ________.

Fuses

________ are made of glass cylinders with thin metal wires, and when the current is too large then the wire heats up, melting, thus causing the wire to break which breaks the circuit and stops the current.

Fuses

________ must have a higher rating than the current.

Current (I) units

Amperes (A)

Direct Current

current that is steady, constantly flowing in the same direction in a circuit, from positive to negative

Alternating Current

current that is continuously changing its direction, going back and forth around a circuit

frequency of ac

number of times it changes back and forth each second

energy transfer depends on… (3)

1. current
2. potential difference
3. time appliance is used for

power

rate of energy transfer or the amount of energy transferred per second

higher resistance

lower current

lower resistance

higher current

Ohms

one volt per ampere

one volt =

one joule per coulomb

Explain the heating effect (2 bp)

* In metals, electricity is the flow of electrons, which is current, and metals are made of lattices of ions, where, then electrons pass through the lattice, they collide with ions, which resists the flow of electrons


* When electrons collide, they lose some energy as they give it to the ions, making them vibrate more, thus heating up the metals

where is the heating effect used

kettles, hobs, toasters