Chapter 4 Elec, Waves, Quantum

Question 1

Equation linking current charge and time?

Answer 1

I=delta Q/ delta t

Question 2

Electric charge is measured in

Answer 2

coulombs (C)

Question 3

Elementary charge is

Answer 3

1.6 x 10^-19

Question 4

Charges of electrons, protons and neutrons

Answer 4

Electron - -e
Proton - +e
Neutron - 0

Question 5

Equation linking total charge number of electrons and elementary charge

Answer 5

Q=ne

Question 6

Define electric current

Answer 6

Rate of flow of charge

Question 7

What are the charge carriers in solutions?

Answer 7

Ions

Question 8

Conventional current flows from

Answer 8

The positive terminal towards the negative terminal

Question 9

Electrons travel from

Answer 9

The negative terminal towards the positive terminal

Question 10

Ammeters are placed in

Answer 10

Series

Question 11

The conservation of charge states

Answer 11

Electrical charge can neither be created or destroyed

Question 12

What is Kirchoff’s first law?

Answer 12

The sum of the currents entering any point in a circuit is equal to the sum of the currents leaving that same point

Question 13

Number density is

Answer 13

The number of free electrons per cubic metre of material

Question 14

Equation linking current, cross sectional area, number density, elementary charge and mean drift velocity

Answer 14

I=nAve

Question 15

What effect does a greater cross sectional area have on drift velocity?

Answer 15

Decreases (if constant current)

Question 16

Three equations for calculating power

Answer 16

P=w/t
P=IV
P=I^2R
P=v^2/R

Question 17

How many joules are in a kWh?

Answer 17

3.6 x 10^6

Question 18

Define the volt?

Answer 18

The pd when 1 joule of energy is transferred per coulomb

Question 19

Voltmeters are connected in

Answer 19

parallel

Question 20

What is thermionic emission?

Answer 20

The emission of electrons through the action of heat

Question 21

In an electron gun the greater the accelerating pd

Answer 21

the energy is transferred to the electrons so the faster they move

Question 22

Define resistance

Answer 22

The ratio of pd to current across the component

Question 23

Define the Ohm

Answer 23

Resistance when apd of 1v is produce by an ampere of current

Question 24

What is Ohm’s law?

Answer 24

For a metallic conductor kept at constant temperature, the pd across the component is directly proportional to the current

Question 25

A photon is

Answer 25

a quantum of electromagnetic energy

Question 26

What are the two equations for the energy of a photon?

Answer 26

E=hf

E=hc/lambda

Question 27

Define the electron volt

Answer 27

the energy transferred to or from an electron when it passes though a pd of one volt

Question 28

Evidence for the wave nature of light includes:

Answer 28

interference and diffraction

Question 29

Evidence for the particulate nature of light includes

Answer 29

the photoelectric effect

Question 30

Work function is defined as

Answer 30

the minimum energy needed to remove a single electron from the surface of a particular metal

Question 31

Threshold frequency is defined as

Answer 31

the minimum frequency of the EM radiation that will cause the emission of an electron from the surface of a particular metal

Question 32

Which quantity is conserved when a photon interacts with an electron is

Answer 32

energy

Question 33

The number of electrons emitted from a metal surface is proportional to

Answer 33

intensity (provided the frequency is above the threshold frequency)

Question 34

Evidence for the wave nature of electrons includes

Answer 34

electron diffraction