2021-01-18
What does “potential energy” mean??
The potential to do work.
How does a stretched elastic band have the potential to do work??
When it is released it will move.
What is potential difference??
The energy transfered per unit charge from electrical energy to another form of energy.
When used to measure a component, what does potential difference measure??
The difference in energy in the charge carriers before and after going through the component.
What does EMF stand for??
Electromotive force.
What is EMF??
The energy transfered per unit charge into electrical energy from another store of energy.
Instead of measuring force, what does EMF measure??
Energy given to charge carriers.
What are the units for potential difference??
Volts, $V$
What are the units for EMF??
Volts, $V$
What is the difference between potential difference and EMF??
- Potential difference measures the energy transferred by charge carries.
- EMF measures the energy transferred to charge carries.
What does a voltage of $100V$ mean??
100J are tranfered per couloumb of charge.
What is $1V$ in terms of $J$ and $C$??
$$ 1V = 1JC^{-1} $$
Some energy is transfered from a chemical reaction inside a battery to the charge carriers in a circuit. Is this potential difference or EMF??
EMF.
Some electrical energy is transfered from a charge carrier to kinetic energy inside a motor in a circuit. Is this potential difference or EMF??
Potential difference.
What is Kirchoff’s Second Law??
The sum of voltages across components that supply electrical energy must equal the sum of voltages across all other components in the same loop.
How could you summarise Kirchoff’s 2nd Law using $\sum$??
$$ \sum \text{p.d.} = \sum \text{e.m.f.} $$
What is the symbol formula for EMF??
$$ E = \frac{W}{Q} $$
What is the symbol formula for potential difference??
$$ V = \frac{W}{Q} $$
What is themionic emission??
The emmision of electrons when something is heated up.
What is an electronvolt??
The energy transferred on an electron when it accelerates through a potential difference of $1V$.
What is the formula for work done ($W$) in terms of a potential difference $V$ and a charge $Q$??
$$ W = VQ $$
Since $W = VQ$, what is one electronvolt in Joules??
$$ 1.6\times10^{-19}J $$
What does an electronvolt measure??
Energy.
How can you work out the speed of an electron??
Equate it’s energy to $\frac{1}{2}mv^2$.
What is the formula for the energy transfered to a single electron travelling from a cathode to an anode over a potential difference of $V$??
$$ eV $$
If an electron has energy $eV$, what could you set it equal to work out the electron’s velocity??
$$ eV = \frac{1}{2}mv^2 $$
2021-01-20
What is the potential difference of the unlabelled component??
$$ 7V $$
What is the potential difference of the unlabelled component??
$$ 20V $$
Backlinks
- [[Physics - Charge and Current]]S
- [[Physics - Syllabus]]S
- [[Physics - Potential Dividers]]S
- [[Physics - Internal Resistance]]S
Metadata
date: 2021-01-18 12:30
tags:
- '@?physics'
- '@?public'
- '@?electricity'
- '@?year-1'
- '@?school'
title: Physics - Voltage and Potential Difference
