P2 - Potential Difference from Batteries

What is a cell in a circuit?

A source of electrical energy with a specific potential difference

What is the symbol for a cell?

One long line and one short line

What is a battery?

Two or more cells connected together in the same direction

What is the symbol for a battery?

A series of alternating long and short lines (more than one cell symbol joined together)

What is the key rule for making a battery?

The positive ends of the cells must all point in the same direction

What happens if the cells in a battery point in opposite directions?

Their potential differences can cancel out

How do you calculate the total potential difference of a battery?

Add the potential differences of all cells connected in the same direction

What is the total potential difference of two 9V cells connected correctly?

18V

What is the total potential difference of three 9V cells connected in the same direction?

27V

What is the total potential difference of two 9V cells pointing in opposite directions?

0V (they cancel each other out)

What happens when one 9V cell is reversed and the other is correct?

The total potential difference is 0V

What is the total potential difference of three cells: two correct (9V each), one reversed (9V)?

9V (because one 9V is cancelled out)

How does a voltmeter help with batteries?

It measures the total potential difference across the battery

How should a voltmeter be connected to measure a battery?

Across the positive and negative terminals of the battery

What does a battery with two 1.5V cells in series produce?

3V

Why does reversing one cell in a battery reduce total voltage?

Because it pushes in the opposite direction, cancelling one correct cell

If you have four cells and two are reversed, what happens?

The two reversed cells cancel out the other two, total voltage is 0V

Why is it important to connect cells in the same direction?

To ensure their voltages add instead of cancel out

What unit is used for potential difference?

Volt (V)

What does potential difference mean?

The energy transferred per coulomb of charge

How much energy does 1 volt represent?

1 joule per 1 coulomb

What happens if one cell has a higher voltage and is reversed against a lower one?

The total voltage equals the difference (e.g. 9V reversed vs. 6V correct = 3V in reverse)

In a correctly connected battery, how do voltages behave?

They add up to give a higher total voltage

If the voltmeter reads 0V across a battery, what could be the reason?

One or more cells are reversed and cancel the others

How does cell direction affect circuit performance?

Incorrectly placed cells may stop the circuit from working