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Flashcards in Electricity Deck (17)
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1

define current and give a matching equation

The rate of flow of charge I = Q/t

2

Define voltage and give a matching equation

work done per unit charge V=W/Q

3

Define Electromotive force and provide a matching equation

work done by a voltage source per unit charge
emf = E/Q

4

give two equations for energy in terms of V

E= VQ
E=VIt

5

Give three equations for power

P = VI = I²R= V²/R

6

Give an equation for resistivity

ρ= RA/L

7

describe an equation to find resistivity

1. measure the diameter of the wire, and find the cross sectional area
2. set up s circuit with a voltmeter in parallel to the wire and an ammeter in series. have a ruler on the wire and crocodile clips determining its length
3. measure V and I for different values of L
4. use R=V/I to find resistance
5. plot R against L and the gradient will be ρ/A

8

state ohm's law.

in an ohmic conductor current is directly proportional to voltage at a constant temperature

9

describe superconductors

a superconductor has 0 resistance below their critical temperature.
they can be used in strong magnets and power transmission

10

In an LDR, describe the trend between light intensity and resistance

resistance decreases as light intensity increases

11

describe an I-V graph for an ohmic conductor

a straight line graph, that intersects the origin

12

describe an I-V graph for a diode

an exponential graph upwards in the positive quarter that goes through the origin

13

state Kirchhoff's laws

total current into a junction = total current out
total emf around a loop = total potential difference dropped across the components

14

describe voltage across components of a parallel circuits

the voltage dropped across components in parallel is the same

15

describe a potential divider.

a group of resistors in series across a voltage source, that splits voltage between resistors in direct proportion to their resistance

16

explain internal resistance

the resistance of the materials across a battery or cell, across which some voltage is dropped

17

what is terminal potential difference?

the potential difference across the terminals of a power source, which is equal to the pd across the load