A-level Waves and Ting G482 Flashcards Preview

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Flashcards in A-level Waves and Ting G482 Deck (83)
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1

Define the Coulomb

The SI unit of electrical charge. 1 Coulomb of electrical charge is the amount of charge transferred by a current of 1Amp in 1 Second

2

Define potential difference (p.d.);

Electrical energy transfered per unit charge when electrical energy is converted to another form.

3

define the volt

1 Volt is equal to 1 Joule per Coulomb

4

define electromotive force (e.m.f.) of a source such as a cell or a power supply

The amount of energy per unit charge converted to electrical from other forms, usually in a cell or power supply.

(N.B. This is almost the exact opposite of P.D.)

5

Define resistance

Resistance, R, in any circuit (series, parallel, or any combination) is the opposition created to the flow of current, I, when a potential difference, V, is applied to the circuit.

This opposition to the flow of current is expressed in Ohm’s Law as R = V/I, where R is the resistance in ohms, V is the applied potential in volts, and I is the resulting current in amperes.

6

Define the ohm

1 Ohm is the resistance of a component when a potential difference of 1 volt is produced per ampere of current.

7

define resistivity of a material

The resistivity of a wire of length "l" resistance "R" and area of cross section "A" is given by p = RA/l

8

define the kilowatt-hour (kW h) as a unit of
energy
 

A unit of energy equal to 36 MJ or 1kW for 1h

9

define and use the terms displacement,
amplitude, wavelength, period, phase
difference, frequency and speed of a wave
 

Displacement-Distance from the mean position expressed as a vector
Amplitude- Maximum displacement
Wavelength-Distance between neighbouring identical points
Period-Time taking for one complete oscillation of a particle
Phase Difference- The fraction of a cycle between the oscillations of two particles
Frequency-Number of waves passing a point per unit time
Speed-Distance travelled by the wave per unit time
 

10

define the terms nodes and antinodes

Node-Fixed point on a standing wave where the amplitude is always zero


Antinode-Fixed point along a standing wave where the amplitude of the oscillations will periodically be at a maximum.

11

define and use the terms fundamental mode of vibration and harmonics

Simplest pattern of movement and has the lowest possible frequency band and the longest wavelength
Harmonics are different modes of vibration of a wave with increasing frequency and decreasing wavelength
 

12

define and use the electronvolt (eV) as a unit of energy

1 eV is gained or lost when an electron moves through a potential difference of 1V


Energy acquired by an electron accelerated through a p.d of 1V.

1eV=1.6×10^(-19)J

 

13

define and use the terms work function and threshold frequency

Work function- the minimum energy required to release an electron from the surface of a material


Threshold frequency- Frequency of a photon that will just emit an electron from a substance without any kinetic energy
 

14

Define the term intensity

Intensity is the (incident) energy per unit area per second

15

state what is meant by the term mean drift
velocity of charge carriers
 

The average distance travelled by the charge carriers along the wire per second

16

state and use Ohm’s law

For a metallic conductor at constant temperature, the current in the conductor is directly proportional to the potential difference across it

17

state and use Ohm’s law

For a metallic conductor at constant temperature, the current in the conductor is directly proportional to the potential difference across it

18

state Kirchhoff’s second law and appreciate that this is a consequence of conservation of energy

Energy is conserved
Sum of e.m.f’s=sum of voltages (total of p.d’s in a loop)
 

19

state typical values for the wavelengths of the different regions of the electromagnetic
spectrum from radio waves to γ-rays
 

Visible 600-400nm (5 x 10-7)
UV-A   400-315nm
UV-B   315-260nm
UV-C   260-100nm
 

20

state three things that electromagnetic waves have in common

Travel at the same speed "c" in a vacuum

All transfer both Energy and Information

All are transverse (travel at 90 degrees to the direction of oscillation)

21

state why polarisers can be used to see deeper into water.

Light is partially polarised upon reflection.

22

State the principle of superposition of waves

When two waves meet at a point and interfere the sum of their individual dislacement is equal to the sum of the resultant displacement.

23

State what is meant by constructive/destructive interference

interference is when two or more waves interact/superpose and there is a change in overall intensity or displacement.

Constructive interference is where net displacement is larger than the displacement of the two original waves

Destructive interference is where the net displacement is smaller that one ( or all) of the original waves

24

What is a photon?

A photon is a quantum (discrete amount) of energy of electromagnetic radiation

25

This isn't really a question - just something you should know:

Energy is conserved when a photon interacts with an electron

You should also know that 

1) Charge carriers in an electrolyte are ions (silly chemistry)

2) Charge carriers moving through metal wires are electrons

26

State what Malus' law is

Malus's law states that the intensity of transmitted light from a polarising filter is:

I = I0cosØ

27

You must also make sure you know all the circuit symbols for 

1) LED

2) Thermister

3) LDR

4) Potentiometer

5) variable resistor

6) plus all the others

Look them up now, go on, it'll be good for you

28

Apply graphical methods to illustrate the principles of superposition

The following diagram explains the effect of superposing two waves that are 1) in phase (top diagram) and 2) in antiphase.

29

Describe how an ammeter may be used to measure current in a circuit 

Must be put in series to measure the current

30

describe Kirchhoff’s first law and appreciate that this is a consequence of conservation of charge

(sum of/total) current into a junction equals the (sum of/total) current out. Charge is conserved