Recall Questions
Define potential difference??
Energy transfer per unit charge from electrical to other forms.
Define the volt??
$$1V = 1JC^{-1}$$
Define electromotive force of a source such as a cell or a power supply??
Energy transfer per unit charge from chemical/other to electrical form.
Define resistance??
$$\frac{\text{potential difference}}{\text{current}}$$
Define the ohm??
A component has a resistance of $1\Omega$ is a potential difference of $1V$ makes a current of $1A$ flow through it.
Define resistivity of a material??
$$\rho = \frac{RA}{I}$$
Define the kilowatt-hour as a unit of energy??
A unit of undergy equal to $36MJ$ or $1kW$ for $1h$.
Describe how a voltmeter may be used to measure the potential difference of a component in a circuit??
Connected in parallel.
State and use Ohm’s law??
When at constant temperature, the current through an ohmic conductor is directly proportional to the potential difference across it.
Why does resistance increase with temperature??
The lattice ion vibrate causing more frequent collisions between electrons and lattice ions, leading to the electrons doing more work as they move through the wire.
Why does current flow lead to heading in components??
Electrons colliede with the lattice ions and transfer some of their kinetic energy to the lattice ion’s vibrations.
What is meant by the threshold p.d. of a diode??
The p.d. at which resistance starts to fall rapidly as p.d. increases.
What happens to the resistance of an LDR as light intensity increases??
It decreases.
What is meant by a negative temperature coefficient component??
One in which the resistance drops as temperature increases.
Why does resistance of a thermistor fall as temperature increases??
The number density of charage carriers increases.
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Metadata
date: 2021-08-03 13:45
tags:
- '@?physics'
- '@?school'
- '@?public'
- '@?energy-power-and-resistance'
- '@?recall-questions'
title: 'Phyiscs - Recall for Chapter 9: Energy, Power and Resistance'